This kind of movie is really played out. The script and acting are both too reminiscent of Juno, the kind of precious, twee affectation that Cera has perfected and needs to put on a shelf never to use again.
As an audience we are rooting for the well-oiled clichè of boy meets girl. What sets Up in the Air apart is its willingness to divert from the superficial and go inside to the uncomfortable truth of life.
I've often debated whether a great ending can salvage a mediocre movie. But does a wholly bogus ending negate the positive aspects of an otherwise solid film? In the case of Nothing but the Truth, the answer is "Yes."