The Happy Atheist is Myers' first book. Readers familiar with his blog Pharyngula will know what to expect. The book deals with religion and atheism from a lot of different angles, and in essence it's a popular book written for a popular audience, using popular arguments. This is not to say that the book is simplistic, just that it isn't scholarly. If you want a preview of the book, read his essay "Planet of the Hats", which in the book is the chapter called "About the Author".
I half-expected the book (having read Myers' blog) to be much more angry than it is. In fact it's a very funny, lively, and readable book, and at no point was I bored. (In fact, I had trouble putting it down. I didn't read it in one sitting, but two.)
The Reason-Driven Life is written as a response and critique of Rick Warren's similarly-titled book, The Purpose-Driven Life. It's structured in much the same way as Warren's book, with 40 chapters meant to be read over 40 days. At the end of each chapter is a Point to Ponder, a Quote to Remember, and a Question to Consider. It's written mainly for Christians who have actually read Warren's book, which I'm not and which I haven't.
It's a somewhat interesting read in that Price is a Bible scholar and really knows his stuff, however the book is meant for someone with a different mentality than my own. So I had to imagine I was a fundamentalist Christian for most of the book. The tone of the book is very respectful, though forceful and to-the-point (all this to say that it's a very personal and honest book). I imagine a wavering intelligent (fundamentalist) Christian would really enjoy it, and maybe even be deconverted by it. Go for it if you're curious, but if you're like me (skeptical and non-religious by nature) you can safely skip it! There are other, better, Price books.