I retrained my high-level PFS Dervish Magus so that he could use the Swashbuckler's precise strike - it was fun. Sure, it cost 2 arcana (well, 1 arcana and 1 feat), but adding 9 damage to (nearly) every attack was a blast. I only used parry/riposte once though - spending that arcane pool point is expensive when you can't recover them.
The other Arcanist exploit that shines to me is the counterspelling one. Being able to counterspell as an immediate action will be pleasant. There is some talk about whether or not you could use a dispel magic slot to counterspell something of the same level, but I haven't seen a definitive answer there yet.
I to am very disappointed with the investigator. It's like they tried to make a factotum, then removed all ability to be effective in combat.
Oddly enough, even though he isn't as good as he was in the playtest, I'm looking forward to test-driving the warpriest. Sure, it's limited to 1/2 level + Wis mod, but free quickened self-buffs are not to be sneezed at. Not to mention buffs to his weapon, armor, abundant healing, and channel energy. It just looks fun.