This is an excellent book.The level of technical detail is below average for the Arizona Space Science Series. This reflects the nature of exoplanet science: it is moving fast, so detail becomes obsolete. This should be contrasted with planetary exploration, where once the data from one mission has been chewed over, that's more or less it until the next mission. There may also have been a desire to keep material accessible to students - who are after all the spur to NASA subsidizing this book's price.The chapters are at a varying level of difficulty. What is common is that the chapter authors lift the lid on the problems of their subfield: both the practical snafus that every researcher must overcome, and the overall constraints keeping a lid on everyone's progress. This is a valuable service.This is a good time to produce an exoplanet science reference book. Enough time has passed to assimilate the first round of Spitzer and Hubble results, although ground-based direct imaging will soon ramp up. Kepler's discoveries orbit faint stars, so they will be difficult to follow up on. As a result, I expect the pace of planet characterization (not detection!) to slow over the next few years.For $25, there's really no reason not to improve your bookshelf with this book if you are an exoplanet researcher. However, if you are an impoverished undergraduate or similar, most of the chapters can be found in finished form on astro-ph (search "arizona exoplanets seager")