As you might expect of a product with over 100 feats, Feats 101 is a bit all over the place. Quickly - formatting is good, grammar and spelling errors are minimal, and the artwork is good though not exceptional. The feats themselves range, some perhaps a bit too powerful, some a bit too weak, but none of them are awful. I'm personally a big fan of some metamagic feats like Shocking Spell which add a rider effect to a spell requiring an additional save instead of increasing the spell level. Some of the Sorcerer Bloodline feats are especially powerful, allowing you to substitute other ability scores in place of Charisma for ALL Sorcerer abilities, though with drawbacks such as giving up an entire school of magic, which do balance it somewhat. Still, something to be careful of when allowing feats from this book. There are also a few new combat maneuvers introduced via feats, Bonded Feats offering more options for animal companions and familiars, two Spell-touched Feats (a 3.5 concept that gives characters supernatural abilities based on their exposure to certain spells), and Talents (special feats only able to be taken at 1st level). Be careful of the Monstrous Physique Talent which allows a PC to increase their size by one category.
Overall a good product, even if there are a few things that might be a little too easy or too good, and well put together, so 4 stars.
[4 of 5 Stars!]