OK, I didn't go directly to the source, as I don't feel it's finished yet, and am commenting on it exactly as it is - and this is my opinion which you asked for.
1) WAY too many "name brand" tags on there. Either figure out some other place to put the "Super Nintendo""SEGA""NEO GEO
""MAME" line on the bottom there (such as small, and to the side of a marquee, perhaps?) or take them off altogether. It makes your CP look WAY too busy.
2) The "Arcade PC" (?) in the top left corner seems WAY out of place - I'd lose it, it "cheapens" the feel
3) The warning - I'd lose it (see point #2 for reasons)
4) The big colored squares - dunno what they're for, therefore, I'd lose 'em. Even if you have a reason, such as "this is where the button goes", I'd lose 'em. Basically, I'd lose 'em

If they're supposed to be button placeholders, make 'em round, and size 'em the same as your buttons.
5) The arrows around the joystick seem to do nothing but get in the way and take away from the artwork underneath them.
6) I can't quite put my finger on what it is, but the font. Something doesn't feel right about it.