I use it on the Mac because it is small and light, and I organise MP3s by album directories with their own M3U playlists and a global large playlist anyway; I rip my own CDs. (Yes, this is considered archaic by some but at least I still have 16bit lossless physical media and fascinating sleeve notes to refer to, right?)
I also have my MP3s by Album Artist - Album directories with their M3U playlists (ripped from my collection), but I don't want to dig through directories, that's why I use iTunes. I can search, get some pretty artwork so I can find which version of a song I'm looking for, add it to a playlist, etc. Cog is a player, but I want a music manager.
Ah I just want a player. I already manage my music - that's what the directories are for. Additional metadata about the albums stored a database isn't going to improve the music for me.
The non-stable version isn't too bad; the current stable one is quite dated for certain.
Additionally, the development version correctly handles VBR MP3s instead of the "stable" one which inaccurately estimates song lengths (ie, a 3.5 minute song is seen as 14 minutes long in the "stable" version).
But for playing MP3s from a list it's great!
If I wanted to manage my iPad with it, do backups, buy music, AirPlay videos, watch videos, rate my music (I already own it, why would I need to rate it?), stream radio stations, copy photos to/from my devices etc. etc. etc. then it isn't so great. That's what iTunes is - a bloated piece of software that is no longer just a music player. You call it capable, I call it bloated :-)
