Up in the Air is a very good movie by Jason Reitman. Jason succeeds in combined screenplay and in his Directorial ability. I liked his other movies, Juno and Thank You For Smoking, the latter *in particular*. I would say Thank You for Smoking and Up in the Air deal about individuals, their professional practice and relationship. Both end up with how their not-so-normal professional practice deprives them of a normal family life. The lead Characters are stoic and end up going through a cycle.
Watch it!
P.S: On an another note, Judd Apatow’s Adam Sandler starred Funny People is worth a watch! Up in the Air and Funny People have an overlapping similarity as their Protagonist is not in to serious relationship.