I like it. I'm no art critic, but here's something you might want to consider: the text. It's a bit harsh on the background. It doesn't 'fade in' to the back ground, which gives it noticeable edges. I think that makes it less pleasing to look at (though it feels 'retro', in a sense).
Take a look at (for example) the original box art:
Notice how the text is calling attention to itself, but it's not as 'sharp' in contrast to the background since it fades into it. If you take another game, for example, Far Cry 3 (chosen because that's the game I'm currently playing ).
I know it's not the best box art ever, but take it as an example. Notice how there is a slight shadow/halo given to the text (if you want a clearer view, go here: http://www.amazon.com/Far-Cry-3-Xbox-360/dp/B0050SYV70/ and click the picture so you can zoom in on it).
If there's not a shadow, there's probably a border that transitions into the background (for example, Mass Effect 3). Again, I'm not a graphic designer, etc. so I don't know what exactly the term is, the theory behind it, etc. Just something I've noticed. Have a look through more to see what I mean, and get some ideas. Portal 2, Call of Duty 4, and Uncharted 2 are also good examples.
Hope this helps :-)