it's a nice idea. the whole image is very clean, but i think it could be more detailed (i know you probably abandoned it after a while). the edges of the cube aren't quite as defined as they should be to reinforce the illusion, and the shading is lacking a bit of dynamic. also, i don't really understand what the background has to do with the illusion as a wallpaper. i get that it's angular and the color kind of works, but it looks strangely "Left4Dead" in a wallpaper with an impossible cube as a focus.

well, that's just my 2 cents. art is subjective anyway, so realistically, you probably made a masterpiece either way. good job!