Finished story mode. The ending didn't make a damned bit of sense (the Bastion's many functions remind me of Professor Farnsworth's glow in the dark nose machine), but the game's amazing atmosphere and mood almost manage to pull it off. Ultimately, though, Bastion's insistence on telling everything through the voice of the narrator might have undermined the story a bit. I did not know, for example, that the Kid and Zia were particularly close, and thus did not feel the intended emotional punch of the final choice.
However, that's really a minor quibble. I stayed up until 3pm playing this game (my usual bedtime is 1 o'clock) because it's incredibly fun and has charm to spare. Repeating the whole thing in new game+ mode is going to be no hardship at all (well, except perhaps for repeating the shield proving ground - that was a pain). In fact, I'm looking forward to it.
My only actual complaint about Bastion is with the save system. So, autosave means that if you die in or quit a level, nothing you did counts. Fair enough. However, the autosave only triggers when you enter a new area, which means that if you mess around in Bastion and then quit the game without first entering a new area, all the stuff you just did (such as customizing weapons, changing your liquors, or buying stuff from the shop) is undone. It's a minor oversight, and perhaps there's some other way to trigger the autosave that I'm not aware of, but it contributed to me staying awake so late (you know, because I'd upgrade a weapon, and then to keep it, I'd go into the dream level, and while in the dream level, I figured I might as well beat it, and in the process of beating it, I'd grind enough gems to get another weapon upgrade . . .)
It's an annoying feature, but not so much that it makes me want to stop playing. The obvious solution seems to be to just never quit . . .