Hell, it's worse.
Zach Galiwhatever doesn't help - actually, to be blutantly clear here: he's one of the most overrated actors of today. For god's sake, the guy keeps playing the same fucking role over and over again! Ever since Hangover, the newest break-out "star" has managed to royally and steadily annoy the shit out of me and force me to use so many swear words in this review that it's getting ridiculous!
Anyhow, Downey Jr. seriously has to reconsider choosing his roles, I have a feeling that Iron Man 2 started his downhill spiral once again (fingers crossed I'm wrong). Cameos such as Juliette Lewis (again being typecast as an addict), Jamie Foxx and Michelle Monaghan do not add anything to the already tiring, boring, lame and completely stale movie that should have been a comedy.
Also, once you realize that it reminds you of Steve Martin's Planes, Trains and Automobiles, you thoroughly lose any interest that, honestly, you never really had. Kudos to the dog - he's got the only hillarious scene in this movie (hint: backseat, car, paw, penis...yup! THAT was the first, gotta say!).
So, let's give it a 5 out of 10. If there's nothing else to watch, go ahead. But, if there is...skip this one!