Other than perhaps individual/personal opinion getting in the way... I have no clue why people have given this title such low ratings.
Tome of Secrets was the first 3PP product I bought for Pathfinder (in late 09, early 2010) and I must say that it's still one of my go-to's for ideas.
Tome of Secrets covers a lot of ground. From ways to modify your favorite monsters, unique races (Saurian have become one of my favorites), Tinker Mages (Artificer) and the best Swashbuckler I've seen for 3.5... to interesting flaws and awesome chase rules. You or your party can take this book to enhance roleplaying (instead of just roll-playing, like many supplements).
Not to mention they will give you a free PDF even if you bought the book from a local store! Now that's service!
I would give Tome of Secrets 4 stars, but I feel that many of the reviews here are very unfair. Especially the 2 and one star ratings that people left NO INFORMATIVE CRITICISM for.
Gamers! Give Tome of Secrets a shot. It's definitely worth it.
Paizo, please crack down on this stuff. Objective and Unbiased versus Ignorant and Careless.
