I think that MAME logo definitely has to be moved. It gets way too lost with the cab and galaxy (or whatever that is). I would say move it to the top because the top is just too boring. There is nothing up there really, and it isn't pleasing to the eye.
I also think that the pac-man maze blocks need a lot of work. It's hard to tell what they are in the version. I would make it so that you can tell without a doubt that it is a pac man level. Otherwise, just get rid of them.
I like the idea of the cabs on it, but as with the MAME logo, I think they get a bit washed out by the galaxy (again, whatever that thing is, I'm no astronomer

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I think this could turn out to be a decent piece of art, although it is definitely not my personal style. I hope I wasn't too harsh, but you did ask to be brutal, heh. Like I said, this just isn't my cup of tea, so I'll prolly never like it, but I hope you'll at least take my opinions to heart because I think that if things were arranged better, it would improve the art a lot.
good luck