Tome and Blood: A Guidebook to Wizards and Sorcerers

A lacklustre sourcebook is a fair description I think. It's a bit lacking in flavour, providing just additional options.

I found the prestige classes to be poor overall, with most of them being rather weird - I don't see why players would even bother with some of them.

The feats are mostly focused on just metamagic feats, so that was pretty limiting. On the upside though, the sourcebook does try to provide some flavour for the metamagic feats, especially between wizards and sorcerers.

Other than these, the rest are just standard fare - a few spells, some magic items (including corny good vs evil item item sets).