I was also a big fan of the ending. The world gets reborn, so I find that a wonderfully happy ending for the original depressing setting we got in Final Empire. In the grand scale of depressing endings, this was pretty light (at least in the way that we don't see a lot of death immediately, just focusing on Vin, Elend, and Sazed). It made sense for them to die. Elend's duralumin + atium was an excellently spectacular method for getting rid of the atium. While I loved Elend--he was my favorite character--his death was just so perfect and essential, the ending could not be anything different. And the only thing Vin could do to defeat Ruin was to sacrifice herself, but that is pretty obvious, really. Opposite forces "annihilating"? Yup, it's awesome.
Really, I would've liked to see more death at the end, like showing more of the kandra dying and stuff. Maybe I'm heartless that way. I think Brandon was not going for a surprise where Vin and Elend die. That's not the surprise, in my opinion; the surprise is what is meant by "Hero of Ages". It's very similar to where Kelsier died in MB1--the death was not the narrative surprise in that one, but his Plan was.
I'm just a huge fan of massive, epic conflict. It's the end of the world, and I loved every minute of it.
I also thought the ending was excellent. Vin and Elend may have physically died, but Sazed writes in his note to Spook that he has spoken to them both, and they are happy where they are. This does two things. First, it proves that at least in the Mistborn universe, there is an afterlife. That makes death a lot more bearable. More importantly, Sazed talks about learning how to put souls back into bodies. If Brandon chooses to, he could have any of the characters in this series be reborn in later books. He probably won't, but the option is there.
Actually, what I got from that is Sazed
can't put the souls back into the bodies.
First, Mists causing Snapping, Sazed as HOA. I called it. Them. Both of them.

Who were Ruin and Preservation? I mean, when they died, they had bodies, like Vin. And you went as far as to describe their hair color (Red and Black, respectively). Preservation even had a prominent nose. Why describe their dead bodies, if they weren't at one time mortals themselves? They created humans, but were at one time human themselves?
Yes, yes you did Qarlin. Good job

*bows*
I think there is another story to be told here. From some of Brandon's responses, he references a "greater cosmology" and Shards of Adonasium. There's more going on here than we know. I expect this greater cosmology is something that will be prevalent in most of Brandon's works, creating a mythology of his own which spans between series. I love it.
Seriously, Brandon, you need to ask Howard to warpgate-dupe you, so you can write these books faster. We need at least three of you, maybe four. Your speed for any one series is great, and we're blessed you can do that one better and actually write two series at a time, but three is stretching you a bit thin, and I count books from 8 different series you're writing that I want more of (Alcatraz, AMoL, Warbreaker, Dragonsteel, MistbornII+, Scribbler, Way of Kings, Dark One) plus those other books you told me about. And I do wish I had the ability to read books you haven't written yet! (Though honestly, if I did have that power, a Scribbler sequel is what I would read first. That book was exciting.)
Was there ever anything to Reen's obsidian?
Reen's obsidian wasn't even a red herring, and you guys spent so much darn time on it! Amazing!
"Dark One"? Sounds interesting, yet I don't think that one has been mentioned on the boards until now.
To be fair, I was right in saying that Reen's obsidian meant absolutely nothing. Of course, I had my own gaffes like my
way too extensive Hemalurgy and mist-causes-Allomancy thing, but at least I knew that Reen's obsidian wasn't important. Ha! In your face!