It's good. I like it. Although I have to concur with LachieD, it looks too flat. Some darker shading and some highlights will make it more toned and 3Dish.

It's alright, however I would strongly advise you against using C# and XNA (I assume you're using XNA). C# is .NET based which means your game is going to be extremely dependant on the framework (something you don't want when distributing). Just stick with basics like Game Maker which I think only requires DirectX. Or if you're really serious try your hand at C++ and SDL. All in all I hope your game goes well .