the main problem I see is that it does not seem to have any depth. The doors seem very flat. Maybe if you slowed down on the gradients, and tried shading manually according to the light source, it would look better. Also, you may want to animate the water, or it would look very odd.
*EDIT*
Yikes! I did not mean to come of harshly. Keep at it. It does not take all that much work to make a presentable BG. Your BG was A LOT better than many firsts I have seen here. Don't give up so easily.
*EDIT*
Yikes! I did not mean to come of harshly. Keep at it. It does not take all that much work to make a presentable BG. Your BG was A LOT better than many firsts I have seen here. Don't give up so easily.