I love this collection of Feats. They are all very well created, and are a nice addition to any game. They can add some really interesting character tweaks. The only issue I have is no table of continence, or feat table for a quick look at what feats are in there.
The collected volumes of Undefeatable for d20/Pathfinder. 90+ pages of feats for all sorts of characters and situations.
A good resource to have. Nothing jumped out at me as particularly broken or munchkin, and I read many feats that were of the very useful sort. Some do seem to blur the line a bit between 3.x feat and 4e powers, but that is not a big deal to me.