The Lunar "Fatsplat" is known among the fan community for traditionally being very weak. The Lunars themselves have a number of play disadvantages, from high charm XP costs, to oddly structured charm trees, making them less a favorite of many players. At the same time, the book does include a good bit of information on the Wyld, and frankly, is the only place you're going to get 1E Lunar information.
I'd strongly encourage you to get the 2E version coming out in April, if possible. At the same time, I'm buying this book for the charms that exist now, and because 15$ isn't that much to me. If you're trying to conserve your gaming dollar, avoid this book, and go for one of the more popular or useful books.
[2 of 5 Stars!]