Eidetic Spellcaster is a horrid ACF...

[icefractal]

For the "average" campaign - not worth it unless you didn't want a familiar anyway, yeah, as spellbook hate is uncommon. However, spell-trading is also uncommon. I've yet to be in a game where the GM:
1) Had friendly/neutral Wizard NPCs show up with any frequency. And ...
2) Did fair trading of spells, rather than "NPCs demand a bunch of gold, don't care what spells you have to show them" or "NPCs demand knowledge of like five spells for every one they give you".

So while the trading-lack is theoretically a big loss, it's a loss that won't matter for most PCs.

And for the games where it is good, it's very good - although as Dragon material it's less likely to be auto-allowed, and the GMs who give Wizard PCs a hard time are often the ones least likely to allow it.