I've had an iTunes account for a few months, now. The player is decent. You can use it to play most formats, or straight from a CD. For an iTunes subscription, pretty much everything is done from the player. Songs cost $.99 I haven't burned any songs, but I know it's possible.
The music itself is in an .m4p format. As I understand it, the .m4p is actually an open, public format, and quite good, technically speaking. I've no complaints about the quality of what I'm hearing. But, iTunes seems to be the only ones using it, and pretty much no other player will handle it, AFAIK.
Songs from iTunes are DRMed. You can play them disconnected from the Internet, but you first have to register/verify your account ID while online. I forget the exact number of computers you can have registered at the same time. I think it's six, but I've only got my home and work computers registered. I have had no problems dropping iTunes files on my keychain and taking them home from work or vice-versa.
The biggest advantage of iTunes is that, once you buy the music, the license is permanent and does not expire. You're buying the music, not renting it. Of course, with DRM in place, and the need to register a computer to play it, there are circumstances I could see that would make the license effectively dead.
That said, I'm not using iTunes anymore. I'm using
Yahoo! Music. Unlike iTunes, it's a subscriber service, which means that if I stop paying them, all the music I've downloaded stops working. It's either $60/year or $8/month for a subscription, but all the downloads are free, unless you want to burn them. If you do want to burn them (done through the player), you pay $.89 per song.
Yahoo! uses the .wma format, which, I think, is supposed to be inferior to .m4p or .mp3. If there are issues with it, though, it's beyond my ability to detect. Yahoo! downloads are also DRMed, of course.
The Yahoo! player is pretty good. It isn't quite as polished as the iTunes player, but it also is still technically in beta. Obviously, iTunes has longer product life behind it. I haven't had any problems playing any downloaded music or existing .mp3s with it, though.
Okay, that probably doesn't sound like a particularly ringing endorsement. So why do I use Yahoo!? Two reasons. The first is because I've used Launchcast (same link) for years. Launchcast is a streaming, customizable radio that I absolutely love. Launchcast uses a ratings system that lets you get a much better "fit" for your tastes than any preprogramed station possibly could. It very quickly adapts to your tastes, has almost all the songs that get broadcast on any FM station, plus it suggests some less known artists that may fit your tastes. I've rated almost 7500 songs over the past fivish years and can't remember the last time it suggested a song I didn't like -- even with much, much fewer ratings, it still gets thing right most of the time.
Launchcast integrates into the Yahoo! player, so you can be listening to the radio and, if you hear something you really like, download it right then and there. For 'free', if you're a subscriber (Launchcast also has a free service with pretty much everything besides the ability to download). That's
really nice. In the last two months of being a subscriber, my .wma library has probably tripled my .mp3 library (which runs back to when Napster was big and I was much less concerned with IP issues), just because the songs are thrown out in front of me without me searching for them (though I can do that, too).
The other reason I like Yahoo! Music has come up as I've started to consider buying a portable player. The iPod plays iTunes files. Period. My .mp3s would be worthless, though I could take the time to convert/reburn my library. Also, nothing else plays .m4p files. In contrast, there are a boatload of players that support .wma and the subscription-based DRM that Yahoo! uses. So, I could pay for every song individually, and lock myself into one type of hardware, or I could select the best from the other two dozen manufacturers on the market plus store 60 GB of songs for less annually than my monthly phone bill and have it integrate with my radio.
