Actually by taking 10 levels of loremaster they lose 2 bonus feats, their familiar progression (if it's not already traded away), and have to spend another feat on Skill Focus (any knowledge).

In exchange they get Lore (which a wizard can already duplicate with a wide array of knowledge skills), some divination spell-like abilities (which are meh), a single bonus feat (so they're down 2 feats), and a few miscellaneous bonuses (either +1 to a few saves or extra 1st and 2nd level spells). Oh and 20 extra skill points.

Those 2 feats can hurt (1 feat is what makes humans so good).