I really like the class, but mostly because its the TYPE of spell caster I've always wanted: One that uses a number of prepared spells that can be freely interchanged for a number of uses.
Because I've wanted this mechanic for so long, I'd love this class even if it had no Arcane reservoir at all. But, giving up familiars, specialty schools, and bloodlines does require some sort of balance, and Arcane Reservoir and Exploits does that pretty well.
Some of the exploits are obviously better than others, but nothing stands out currently as absolutely broken.
I agree with everyone's opinion that regarding the damaging exploits, Flame Arc's reflex save seems to not be worth the net 1 point of damage (on average) per die rolled.
I like the idea that the actual Arcane reservoir equals 1 + 1/2 Arcanist level, as that isn't a lot, and how there are no "roll-over" reservoir points. It COULD be tweaked, I suppose, to make it more charisma related, like the reservoir refilling equal to the Arcanist Level + Charisma Bonus + 1. or it could just be tweaked down a bit to 1/2 level + Charisma Bonus (minimum 1). If relative power level seems to be the biggest overall concern by players, this alone should greatly resolve the issue.
I like the flavor the reservoir and exploits provide. I think there is a place in my game for such a class.
I've played Wizards, and I've Played Sorcerers. I still see reasons to play both of those classes even in a world where Arcanists exist.
I get that some people will feel like it gives too much of what people like about the Sorcerer and Wizard classes with not enough of the downsides. I don't really have an argument for that as so much of what people want is subjective. Some players see familiars as a liability while other see them as a huge advantage. Some people see spell books as all advantage and no downside, while others see them as a liability as they can be stolen, set on fire, lost, damaged by fungi, mold, vermin, liquids, stains etc. It depends on your play group, your GM, and your collaborative play style.
Final Opinion:
I can't speak for everyone's game, but for ours the Arcanist as written is a reasonably balanced addition to the available spell casters (though it might be tweaked a bit with a slightly smaller number of refilling reservoir points) and will appeal to many players, myself included, because of the overall flavor and the mechanic for a mix of spontaneous and prepared spells.
Sometimes popularity can be a warning bell for OP. Sometimes, its just a sign of "something that's been missing that players want". I see this as more of the latter than the former.
