5 out of 5 rating for Book of Lost Spells
(NOTE: This is a review of the PDF. I didn't buy the hardcover version.)
This is the first 3rd-party product I've ever bought for D&D, so I wasn't sure what to expect. Suffice it to say, it was amazing. The spells are enormously varied. From the obviously-inspired-by-Water-Breathing "Air Breathing" to the extremely specialized "Locate Fish" to the terrifyingly overpowered "Quicken Assassin", which is basically the "Ice Assassin" spell from 3.5, there's something in here for everyone. For the love of Pun-Pun, only let your players have this spell if you either love freedom in your game or routinely throw packs of tarrasques at them.
The only complaint I had was with the art inside. It was all black-and-white, and while I understand that was most likely done to cut printing costs, couldn't they have had a colored version for download?
All in all, it's glorious. I particularly love some of the specialized uses of sorcery points in Dragon's Gauntlet, Rainbow Spear, Rainbow Staff, and Slimeball. With some clever play, this book could make a Sorcerer a viable competitor to a Wizard. But by far the greatest part of this book is just its breadth. I fully recommend it to the lover of magic whose appetite wasn't satisfied by the Player's Handbook.