I'm not really looking for input on whether or not you like teamwork feats themselves, but rather on the balance of the feat I designed. In this case, the GM is giving everyone a free teamwork feat, so yes... otherwise I might not have taken a teamwork feat at all... especially in the RPOL environment where I don't really know any of the other players. A feat that relies on another character (or characters) having the same feat and using it in tandem with your character is a hard sell unless you know the other player(s) and know that they will coordinate with you. This particular feat is, to me, a bit more useful in that it allows characters with area-of-effect spells to use them a bit more indiscriminately.
As for it granting Evasion, it only grants it vs. your teammate's spells, which is a far sight less powerful than granting it against enemy spells, especially when you consider:
Selective Spell (Metamagic)
Your allies need not fear friendly fire. (
http://paizo.com/pathfinderRPG...d/advancedFeats.html)
Prerequisite: Spellcraft 10 ranks.
Benefit: When casting a selective spell with an area effect and a duration of instantaneous, you can choose a number of targets in the area equal to the ability score modifier used to determine bonus spells of the same type (Charisma for bards, oracles, paladins, sorcerers, and summoners; Intelligence for witches and wizards; Wisdom for clerics, druids, inquisitors, and rangers). These targets are excluded from the effects of your spell. A selective spell uses up a spell slot one level higher than the spell's actual level.
Spells that do not have an area of effect do not benefit from this feat.
True, this feat does require a spell slot one level higher, but it doesn't require a saving throw at all, much less an "evasion clause." It also does not require excluded targets to have the same feat. Hmm, I probably should add the requirement in my feat that the spell be instantaneous and note that helpless allies do not benefit from the feat.