I've been reading a lot of reviews, and really.. I don't get it. Sure, taste and preference are a big thing, but I felt the ending was perfect.
Scarlett's realization is what gave her power. Her whole quest finally led her to the truth of the stone, and of alchemy (and by extension, magic in general imho) I'd compare the hell here to that in "What Dreams May Come", which i felt was a perfect example of personal hell (I'm atheist btw, just so we're clear there's no "real" belief swaying me) where one's torment was actually caused by one's self, and not some outside punishment. I never really liked the idea that hell was eternal, but rather more like purgatory, which I felt is where they actually ventured.
We don't know what happened to the other's afterwards, perhaps they finally found redemption, or maybe they're still there. The fact that the passage changed well before they even reached the resting place of the stone, could have several meanings. Perhaps the stone itself (Flamel, since the stone wasn't actually the stone, but rather the realization of "magic" was) caused the "purgatory" state to begin, or maybe it was their actual seeking of it that caused it. Gonna need a few more watches and some time to think ;p
The end though, I felt it was great. Her basically "bitch slapping" the gargoyles to me, seemed to show that she had abandoned her fear, which gave her strength. This was confirmed (again, imho) when she came back to the arms trying to drag her into the blood (and omg, how cool were the mouths in the ground?!? Barely there but wow, that was awesome!).
The end did feel a little rushed though, I really hope there's some extended/director's/unrated edition that will come out with extra scenes, though I really only mean after the part where she heals George. I'd love it if there was some more contemplation, and confession before the jump into the final escape. I feel like that part could've been another 10-15 minutes, but that it wouldn't really "sell" to the masses for a theatrical release.
And while not really an issue, I'd have also liked a bit more leading up to the entrance of the catacombs. Interviews, questions, discussions. Not really needed, but would be nice, but then again.. running time.