It doesn't really have that sonic feeling. As Jason said, it's like a generic look that you'd expect to see in games like puggsy, chuckrock and rolo.
It might be because of the tiered foreground. I don't think it's something I've seen in Sonic before, at least not like that. If you're going for underwater sea, have it more sandy, perhaps with some coral and starfish like you have done in the background. Of course I base that on the assumption that Sonic is already underwater (despite the lack of underwater palette on Sonic, it looks as if he is already underwater)
The sunken ship looks too intact to be a sunken ship. break it up more, make it more diffused and add more debris. After all, in the deep sea, you're not likely to see that much clarity in a sunken ship and it's not going to be that clean (add moss and coral to it) . Also add coral and more rocks to the background around the ground. The sea floor looks too level.
Just to give you an idea of what I mean about diffused look.http://media.nowpublic.net/images//f1/0/f1...15b51da60a7.jpghttp://soulofamerica.com/soagalleries/caym...sunken_ship.jpg
Just to quickly add, it also looks like the boat is a rather small boat given the size of the planks on the side of it, which in turn makes it look like the boat is right up next to Sonic given its scale. I think you should add more planks to make it look larger and then implement some of the other suggestions and then hopefully it will start to fall in place.
This post has been edited by EnterTheHatrix: 21 April 2010 - 06:06 AM