Although I'm fairly partial to Roland instruments, even some of my friends have commented on the quality of the tones. I don't really like the sequencer, but I've never seen the point in using a hardware sequencer when software based sequencers can be upgraded. If anything, I'd swap the sequencer for more polyphony, but other than that, it's my favorite instrument.
Comments About the Sounds:
(Thanks to Chris D. Stark for this info.)
and http://www.mawek.com/roland/xp for the pic