I've read many, many reviews of this book. Most of the criticisms are from people who want less practical steps and more theology and philosophy behind the church's ecclesiology and such.
Here's the deal from my perspective. Searcy starts out at the beginning of this book, and every book, by saying "here are the nuts and bolts" and "if you want the theology behind this, there are plenty of other books written".
So if you're looking for something other than practical tips that he's used effectively, then you'll be dissatisfied. (You should also probably read his introductions too before buying, since he's plain about what his books are...and aren't.) However, if you want the step by step process that he and his team have used to coach many successful church plants, then this is the book.
After 12 years of pastoring in a bivocational urban church, we set out on a journey to plant a new church in a new area with a strategy to "launch large".
Our strategy to reach new people for Christ has been very effective and we're thankful. God has been so good and has blessed us greatly. We're genuinely humbled and thankful for the results of the plant. (Launched with close to three hundred in attendance, still averaging over 200 after 20 weeks.)
We assimilated and formulated our strategy in large part based on three different resources. 1) Training from the ARC (Association of Related Churches) - They have planted over 200 churches using a "large launch" strategy with over 90% success rate. 2) This book "Launch" from Nelson Searcy. 3) To a lesser degree, we picked up some follow up strategies from Stetzer's book "Planting Missional Churches".
So for us, we were looking for strategy, we found it here, we employed many of the strategies in the book and God gave the increase by allowing us to experience the results we were praying for.
I have nothing but positive things to say about Searcy and the book "Launch".