Love the idea. Very colourfull.
Are you aiming at a correct perspective on the water, or something more abstract? If the ground is the same level as the water, the size of the boat doesn't make sense, even if they're on top of a cliff, you would have to adjust the angle of the boat as you can see a lot of the roof right now.
The peaks on the mountains could use some AA, and the clouds have 3 extra AA colours I can hardly see.
I guess the thing I notice the most though is the powerbar. If this were a game, I'd have problems reading what it says. The bars blend with he metal outlining and the hard to read numbers cover it up. I like the smooth road, but the plants make me wonder what it would look like with some texture. The main characters left arm blends with his scarf a bit, maybe by giving it some more volume would help, though animation should fix that.
Just wondering... Is there some Viewtifull Joe inspiration in here? I see: a cool concept, hero with scarf and gassmask badguys with stripes. Great stuff none the less. I'd play it.