Well, I decided to try iTunes out also. It all seems fine and dandy and very easy to use. I agree with Jark's review, but there were a few things left out of the music limitations. From what I discovered (and correct me if I am wrong) was:
1. Youre screwed >

You can't transfer your purchased m4p/aac tunes to your player unless it's an iPod.
2. You're screwed >

You can't convert your purchased m4p/aac tunes to the mp3 to then transfer to your mp3 player if you don't have an iPod. There is an option to 'convert to mp3' but it ends up just telling you that you are not allowed to perform this on purchased music.
3. You're not screwed

You can only listen to your tunes on up to 3 pc's authorized with iTunes software. Home and work will probably be most peoples locations so this is an acceptable thing.
It seems to me, anyone with an older player (mine is an Archos Jukebox 10) you're going to be limited to listening to your purchased iTunes on your PC and not on the go (unless you use a portable CD player).
Just thought you'd like a little more info before you think about trying it. If I am wrong about the above, PLEASE let me know as I don't want to mislead anyone (and I wouldn't mind getting these tunes on my player).