I like it a lot. The player, not the online store. It does everything I want it to do, and not too much more. And the unicode support is good. (both in the id3 tag support and the dealing with file names in windows, RealOne and VLC won't play my files with thai name)
20MB download is not small (this includes bundled Quicktime) but it makes good musical experience and is very elegant looking (like most Apple stuffs).