Ok I tried it......
I agree with every point aradecab brought up.
Mainly filters are a must.... with mame's gamelist reaching up into the thousands, nobody is willing to manually tweak a gamelist anymore.
Also the config utility doesn't work at all.
Even if it did work the captions for the marquee path and snapshot path are swapped.
Gaphically I think you've done a great job.... One bit of advice though.... do youself a favor, go to crashtest's page and download some borderless snaps. The cube doesn't look bad at all with his snaps, apparently the retarded mame32qa snaps are so ugly they can ruin 3d renderings as well.

Rounded cube looks nice.

While we are on the subject... just an opinion....
I noticed you inheriantly wish to support mame32. While I think this is admirable, be prepared for some of the stupidest users asking some of the stupidest questions ever. Sure mame32 is very popular, but so is eating paste. Like the paste eaters of the world mame32 users, in general, are young, have limited computer experience and possibly head trauma.

About naviagtion.... the wheel spins very fast! Good job getting such a fast render. Unfortunately on more powerful systems it spins so fast that you can't stop accurately. I think you need a scroll speed option. Also while you are messing around with inputs, why not add in the ability to scroll via a mouse axis? Then people with spinners would really have something to show off.
A couple more things that probably have to do with it's "beta-ness":
When mame launches you kill the window and resize it, causing the desktop to show. I'm aware that you usually have to kill the rendering upon launch so it can be re-initalized after the game is over, but a nice, fullscreen, blank form would be nice so we don't to actually see it.
What no sounds? A silent fe is a boring fe imo. A nice "price is right" style click when you scroll through the wheel would be nice. Configurable sounds would be better.
Background music would also be nice.
Also about the marquees..... When I don't find one in my fe I take a "notfound.png" and overlay the game name on top of it. You might wanna try it, as it looks far less "pregenerated". Same goes for the snapshots.... nothing is more annoying than big white text that says "snapshot not found".
Overall tremendous effort..... I think this fe will turn out really nice, just keep on it.