I just got back from MU - I enjoyed it and give it a solid B+. It's not top-tier best-picture-worthy Pixar (insert Up, Wall-E, TS3, whatever your favorite here), but I liked it better than I expected to. I think it helped that I managed to avoid a lot of spoilers - Act III was a complete surprise and really made the movie for me (starting with the "gasp!" moment when you realize what really just happened - then why. Sorry for being obscure, trying not to spoil.). Loved Helen Mirren, and I was surprised and happy to hear Pete Sohn's voice (Pixar animator who was Emile in Ratatouille). Enjoyed Randy Newman's score and the callbacks to his original Monsters Inc music.
I'll be honest, I was not a fan of Blue Umbrella. I felt like Paperman did a similar story with miles more charm, and I'm not a fan of "ooh, look, gritty photo-realism!"
The "Frozen" trailer played like a great old Pixar short, though, and I think it got bigger laughs than MU. We got the "Planes" trailer and while I don't anticipate paying to see it, they certainly did amp up the production values on this. (Have we all noticed, too, it's being released as Disney and not Pixar?) Not Disney, but we also got the Despicable Me 2 trailer - I already knew I was going to see this, but it looks like fun.