The cabinet art looks really good!
The backglass doesn't look too bad... though it could be improved IMO.
The colors are good.
Paul Stanley's legs are kind of in a weird position (he's standing funny)... the perspective looks a bit off (we can see the top of his boots even though we're looking up at him)... Ace Frehley's jaw looks disjointed.
Overall the silhouette shapes (positive vs. negative space) could be improved (there are plenty of tangents)
Tangents: http://emptyeasel.com/2008/11/18/avoiding-tangents-9-visual-blunders-every-artist-should-watch-out-for/
Silhouette shapes in art: http://thevirtualinstructor.com/positive-and-negative-space.html
That said, I like the dynamic angles and the colors.