Mr. Magniloquent
Arcane
The EK class feature to quicken a spell after a critical hit is not very good. If you've scored a critical hit, the thing should basically be dead anyway. It might be useful in a large battle where you can DPS a boss then slap down additional CC or AoE for the mooks, but...meh. Unless you're playing easy mode or using Selective Metamagic, that probably won't work well. If you're going Trickster Mythic you can chase crits with ray spells, but it's not worth the effort. Best mileage out of its virtues is to focus on CC and dispelling, then attacking with weapons. The BAB boost is nice, but comes a bit late, so the CC is almost need to have rather than just nice to have. I agree that hanging out near the frontline for AoO is also ideal.