It's simple but it works. I quite like it.
I agree with the stuff Howard said.
Also your texture is a very fucked up size. Normally game engines handle sizes which are powers of 2, 8x8, 16x16, 32x32... you get the idea. Some can do mixes of those as well, like 64x128 and such.
I made an edit of your texture.

If you can manage to have the edges connected in the UV like in the model it is not a bad idea in most cases (esp when doing higher resolution textures). So you can kinda unfold it like a box. You can still unwrap the shapes seperatly if you want but you can then weld the vertexes on the UV to get the stuff back together.
To get the texture into an 64x64 I gave sides with little information less space. The light grey on the left and right does not need more than a 1 pixel line (1 pixel really, but because of the whole box unfold I made it a line). And the top bit on the back can have 2 pixels I think. That way you also get more space for a controller

I also tinted the grey a bit blueish, makes it look less boring I think.
Keep it up.