Suffice to say, the rest of the film isn't that funny either. The main running gag here is Mortdecai's mustache, which I guess is supposed to be funny in and of itself. Having grown it just weeks before the story begins, Depp's character spends most of the movie defending his bristles, chiefly to his posh wife Johanna (Gwyneth Paltrow). Other than that, most of the jokes rely on Mortdecai's inability to fend for himself, as he calls upon his trusty manservant Jock (Paul Bettany) to fight for him. It's sort of a Clouseau/Cato dynamic, but with nowhere near the same amount of charm. Overall, the humor is flat and predictable.
In fact, the only real surprise here is that Mortdecai was able to lock down such an all-star cast. In addition to Paltrow and Bettany, the film features appearances from Ewan McGregor, Olivia Munn and Jeff Goldblum. However, with Depp chewing up most of the scenery, the rest of the cast gets saddled with paltry, one-note side characters -- particularly Goldblum and Munn, who don't even show up until the last 20 minutes of the movie.
The only other positive thing I can say about Mortdecai is that Koepp's direction is surprisingly flashy and fun, which at least keeps the film from being a total waste. Clever composition and smooth camerawork give the story a brisk and whimsical feel, while the numerous scene transitions are marked by impressive, globetrotting graphics. If nothing else, you can tell that Koepp and Depp are having a ball with Mortdecai; it's just a shame we can't enjoy it too.