Pros: 48 gb memory with 32gb sdhc card. Hardware buttons for FF or Vol. Good SQ.Cheap if used. Can install Rockbox on it. 30h battery life on flac.Repl bat
Cons: Sound on the warm side. Touch screen a bit too large for some people. Somewhat buggy and clunky UI, but can use flash ui alternatives.
It's well built, has good sq (natural if a bit warm sound if you turn off all the enhancements), outstanding battery life(and you can replace the battery with nokia ones afaik), shdc expansion and ample internal memory. Supports mp3,wma,flac and ape, ogg, etc. Otherwise, read the pros/cons. The internal amp has plenty of power to drive HP even being able to drive my D5000 for a few times I was insane enough to use it as a portable. No problems with any IEMs I had either.
UI is a bit buggy and the player refuses to play some files with tags (about 0.2%), but then you can easily strip those tags. Still, there's folder or music library file mgmt, ample sound enhancement options, radio, voice recorder... May just no line out =(...
Rockbox is always a welcome alternative to native firmware, and thanks to the contributors it's been maturing nicely.
If I was to buy a player now, even after two years I'd very likely pick the D2 - sure it won't play hd vids or make coffee (and maybe the screen is not quite as nice as the new oled amoled, etc), but as a music player it's unmatched in value and features to date.
edit:notably, cowon still provides firmware updates. http://iaudiophile.net/forums/showthread.php?t=38086 not that it would need them if everything worked, but at least they fix the things that don't.