The emblem, sword and logo are cool, everything else could use some work. Good luck in the competition.
Edit: Sure, the texture you applied to the pizza slice looks flat, which CAN work in some instances where the aesthetic is stylized... but not here since you already established that things are detailed in this "world". Specifically the 3 things I praised originally, they're all more polished than the pizza and the girl. Generally, the subject is supposed to be greater than or equal to the supporting material in terms of detail. So while you clearly put a lot of effort into that shark, it actually made the whole picture worse overall because it created an imbalance.
Then there's other things like the anatomy (which I almost always harp on), the general shape of the pizza isn't that pleasing to look at and there's rough edges in a few places. The pose actually isn't that bad, but like someone else said: the line art is better in some ways. For example, I didn't know she was holding a pizza cutter until I looked at the line art. In that respect, you failed to communicate that she was holding a pizza cutter. The line art also looks better because without the logo fighting for attention, it's easier to focus on what the picture is really about. There's a nice flow in the lines that's completely missing in the final piece, and that's not a uncommon problem in the art world.