Book Review

Growth Hacking: What the Book Gets Right — And What Small Teams Actually Need to Know


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Jan 25, 2019
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A 15-year digital marketing consultant reviews Growth Hacking by Sean Ellis — and separates what's genuinely useful for small teams from what only works if you have a full engineering department.
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Book Review
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Published
Jan 25, 2019
📖 Reading time: ~11 minutes

💡 Quick Answer Growth hacking is a data-driven approach to finding your fastest, cheapest path to user growth — originally developed in Silicon Valley startups but applicable to teams of any size. The core tools that actually work without an engineering team: finding your product's "aha moment," defining a single North Star Metric, and running small structured experiments before committing to any channel. Here's what the book teaches well and where it needs translating for real-world use.

The Client Who Couldn't Figure Out Why Growth Had Stalled

A few years back I was working with a small e-commerce brand — three people, doing decent revenue, stuck. Traffic was coming in. Sales were happening. But growth had plateaued in a way nobody could explain, and the founder's instinct was to spend more on ads.
Before recommending anything, I asked her one question: what does a user do in their first week that predicts whether they'll come back?
She didn't know. She had revenue data and traffic data but no understanding of what moment — what specific action — turned a new visitor into a customer who returned. She was optimising the top and bottom of her funnel without knowing what was happening in the middle.
That question — and the process of answering it — is essentially what Growth Hacking by Sean Ellis and Morgan Brown is about. Ellis coined the term "growth hacker" and built the methodology behind it at companies like Dropbox and Eventbrite before writing this down. The book formalises an approach that had previously been practiced informally at a handful of Silicon Valley companies and makes it accessible to everyone else.
Whether "everyone else" can actually use it depends a lot on their situation. More on that shortly.

What Growth Hacking Actually Is

The term gets thrown around loosely enough that it's worth being precise about what the book actually means.
Growth hacking is not a collection of clever marketing tricks. It's a systematic approach to finding growth through data and experimentation rather than intuition and assumption. The core loop: form a hypothesis about what might drive growth, design the smallest possible experiment to test it, measure the result, keep what works, discard what doesn't, repeat.
What distinguishes this from normal marketing is the emphasis on speed and data at every stage. Traditional marketing campaigns take months to plan and execute and often produce results that are hard to attribute clearly. Growth hacking experiments are designed to be fast, cheap, and measurable — the whole point is to generate signal quickly so you're not committing large resources to approaches that haven't been validated.
The Airbnb case that gets cited constantly — where the founders discovered that poor-quality host photos were suppressing bookings and personally visited hosts to take better ones, resulting in a significant jump in reservations — is a good illustration of the method in miniature. They didn't assume the problem was marketing spend or platform features. They looked at the data, found the friction point, tested a specific fix, and measured the result. The solution was obvious once the problem was correctly identified. Finding the right problem is the hard part.

The Three Ideas From This Book That Actually Hold Up

After fifteen years of working with brands across North America and Greater China — from international consumer names entering the Chinese market to small founder-led businesses trying to grow their presence on Xiaohongshu or TikTok — three concepts from this book have proven genuinely durable.

1. The "Aha Moment"

Every product that retains users has a specific moment where the user gets it — where the value proposition stops being abstract and becomes real. Ellis calls this the "aha moment." For a ride-hailing app, it's the first time a car arrives faster than you expected. For a recipe platform, it's the first time you cook something from it and it actually works. For a B2B tool, it's the first time it saves you an hour you needed.
The aha moment matters because it's the gateway to retention. Users who reach it come back. Users who don't, leave. And most products have no idea where their aha moment is because they've never tried to find it systematically.
The practical exercise: look at your retained users — the ones who have been using your product or service for more than 90 days — and find what they did in their first week that your churned users didn't. That pattern is usually the aha moment, or close to it. Once you know it, you redesign your onboarding to get every new user there as fast as possible.
I ran a version of this exercise with that e-commerce founder. Her retained customers had almost universally browsed the "how to use" content before buying. New customers who went straight to product pages and bought without that context had much higher return rates and much lower repeat purchase rates. The aha moment was understanding the product before using it, not the purchase itself. We added guided content into the post-purchase flow. Repeat purchase rate went up measurably within six weeks.

2. The North Star Metric

One of the most useful and most misapplied ideas in the book. The North Star Metric is a single number that best represents the core value your product delivers to users — not revenue, not traffic, but the metric that most directly indicates whether users are getting what they came for.
Facebook's is daily active users. Airbnb's is nights booked. A messaging app's might be messages sent per user per week. The point is to choose one metric that the whole team optimises toward, because most growth teams fail not from lack of effort but from lack of focus — they're pulling in slightly different directions because they're watching different numbers.
For small businesses, this concept is liberating rather than constraining. Instead of tracking fifteen metrics and feeling overwhelmed, you pick the one that matters most and ask, every week: did that number go up or down, and why?
The caveat Ellis himself acknowledges: choosing the wrong North Star Metric can be damaging. Optimising for a proxy metric that doesn't actually reflect user value can produce numbers that look good while the underlying business weakens. The work of choosing the right metric is not trivial, and it requires genuine understanding of what your users actually value — which loops back to the aha moment work.

3. Structured Experimentation Over Gut Instinct

The part of growth hacking methodology that most small teams underuse is the experimental mindset — the habit of treating every marketing decision as a hypothesis to be tested rather than an assumption to be acted on.
This doesn't require an engineering team or expensive tools. At the most basic level it means: before you commit significant time or money to a channel or approach, run the smallest possible version of it and measure the result. Post three times a week on a new platform for a month before building a full content strategy for it. Test two different email subject lines before scaling an email campaign. Run a small paid budget on two different audiences before deciding which one to invest in.
The discipline of treating these as experiments — with a specific hypothesis, a specific metric, a specific timeline — changes how you interpret the results. You're not "trying things and seeing what happens." You're testing a specific prediction. When the result comes in, you learn something specific, whether it confirms or contradicts what you expected.

What the Book Doesn't Prepare You For

I want to be direct about this because the book's case studies — Airbnb, Dropbox, Facebook — can create an impression that growth hacking is primarily a technology company methodology.
A lot of the tactics in Growth Hacking require engineering resources that most small businesses simply don't have. Referral programmes with automated tracking. Personalised onboarding flows based on user behaviour. A/B testing at scale. These are powerful tools and they're worth knowing about. They're also largely inaccessible to a one-person operation or a small team without a developer.
What IS accessible to any team, regardless of size or budget:
  • The aha moment discovery process — this is a question of looking at your data, not building new infrastructure
  • The North Star Metric — choosing one number to care about most is a decision, not a technical project
  • The experimental mindset — running small, structured tests before scaling is a habit, not a tool
  • The customer lifecycle thinking (the AARRR framework: Acquisition, Activation, Retention, Revenue, Referral) — mapping where users drop off is something any business can do with basic analytics
The honest reality is that the social media platforms have done a lot of the infrastructure work for smaller operators. TikTok's analytics, Xiaohongshu's creator insights, META's ad testing tools — these give small teams more experimentation capability than Dropbox had when Sean Ellis was growing it. You don't need to build the testing infrastructure. It's already there.

Growth Hacking in the Chinese Market — One Difference Worth Noting

One thing the book doesn't address, which has been relevant in my work with brands entering or growing in Greater China: the platforms themselves are more active growth partners in the Chinese market than their Western equivalents.
On Xiaohongshu and Douyin, the platform's growth incentives and the brand's growth incentives are more explicitly aligned. Platforms actively surface and amplify content that performs well, provide direct data on what's working, and create commercial tools that small brands can access relatively easily. The growth hacking principle of "find what's working and do more of it" maps very directly onto how these platforms want their brand partners to operate.
The aha moment concept is particularly useful in this context. On Xiaohongshu especially, the content that converts — the post that takes a browser to a buyer — often hinges on a very specific moment of recognition: a user who is exactly like me, solving a problem I have, using this product. Finding that specific signal and replicating it deliberately is growth hacking applied to content strategy. The methodology is the same. The tools are different.

Who Should Read This

Growth Hacking is worth reading for anyone who manages growth for a product, service, or brand — which, if you're a founder or a solo marketer, means you. It's clearly written, well-structured, and the case studies are genuinely instructive even when they're not directly applicable.
Read it for the frameworks, not the tactics. The aha moment, the North Star Metric, and the experimental mindset are ideas that will change how you think about marketing problems, regardless of what tools you have available. The specific tactics — the referral mechanisms, the automated onboarding sequences — treat as things to work toward rather than things to implement immediately.
The book that pairs well with it: Hacking Growth (same author, different title in some markets) covers similar ground with more recent examples. If you want to go deeper on the metrics and analytical side, Lean Analytics by Croll and Yoskovitz is the best companion read.
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