First impressions:
I don't like the blue text on blue background on the main library screen. Is black/white too uncool?
Because it's designed for landscape mode, some of the dialog boxes overrun the screen area on the SL-6000.
ev1l is right about the English messages. Sharp have allocated zero budget for translation.
NO AAC (MP4, M4A) SUPPORT. Screw Windows Media. This is one area where Apple's format has a hefty presence on account of the iPod, and yet the support in third party devices is rubbish. (And I'm not talking here about locked DRM .M4P files. That I can understand.) Meantime Kino will play these files but doesn't read tags.
On the other hand...
It did a great job of finding my library. I also like how the user can specify which files to use instead of showing an aggregated global search. Man, that's annoying. It's also possible to limit the library to certain keywords, which is also like searching in a way.
The key (i.e., non-screen) access is nice. Not as customizable as Kino, but it does the trick.
I also like the way it reads embedded IDv3 tags and allows users to select a "reference image," which I'll use for cover art. Though this feature seems to be crashing the app now that I'm playing with it.
All in all it does a better job than Kino/Mplayer at reading and organizing MP3s but I'm not sure if that's enough to make it my primary player. What I'd like to see is a single player that combines the strengths of the the existing ones while adding full OGG and AAC support.