Up, while technically brilliant and often gorgeous to look at, is one of the bleakest movies we've ever seen. The first 10 minutes of the movie are fascinating to watch, but veer into serious tear-jerk territory fairly quickly. The rest is just bleak and weird, with a few minutes of heartwarming content at the end. The dogs are cute, though.
Up in the Air is also bleak -- but it's supposed to be. It's a very sardonic, and an actual adult comedy (R-rated, even), and has some real bite. It also has George Clooney, Vera Farmiga, and Anna Kendrick (who is (a) young and (b) very good). It may not make cinematic history, but it's a solid couple of hours of film, and I strongly wish there were more movies like it.