I finally saw Men in Black 3 and I was totally blown away. It's my second favorite 2012 movie so far. They did an excellent job with the characterizations, the humor, the action and Josh Brolin did such a good Tommy Lee Jones that it's scary.
I saw both Snow White movies this week. Mirror, Mirror strove to be a hip retelling of the fairy tale with some sly digs at the genre. It worked in the Shrek movies, not so much for this. I think they tried to be silly when they should have played it straight. And most of their attempts at humor fell flat for me. However, there were some excellent moments. I liked the mirror gimmick, having the Queen talking to her own reflection was a clever idea. I also liked the ending.
Snow White and the Huntsman tried to get a darker tone to the tale, more like a Grimm tale than a Disney story. This had more internal consistency than Mirror, Mirror. It didn't work for me, though. It had a lot of interesting ideas, but never seemed to follow through with them. The reason the Queen was so eager to kill Snow White made sense and there were a lot of good scenes. (I particularly liked any scene with the magpies.)
My favorite 2012 movie so far is The Avengers! w00t! It was everything I hoped for. Humor, explosions, great characterization, explosions, a few fights between the heroes, more explosions, the team coming to know each other, yet MORE explosions, the final battle (which had lots and lots of explosions) and a satisfying ending. (Which sadly, had no explosions, but one can't have explosions in every scene.) (Not even on Mythbusters.)