I've been playing with it since getting off work. So far I really like the navigation and ease with which you can buy music. And its not $10 per album across the board, there are some albums that cost a little more. Right now is not the best time to be on there as there are routinely some timeouts and connection problems from all the Mac addicts flooding the servers. I was able to successfully download a couple of songs before the servers got too busy.
I also ordered the 15GB iPod. I had been wanting to get one for the last couple of months, but I knew they were close to a new model release. Supposedly it will arrive by this Friday, which I hope is true, so I can play with it over the weekend.
And I'll probably be re-ripping some of my CD's to the AAC format. You can convert existing MP3's to AAC, but the quality isn't going to be quite as good compared to ripping straight from the CD to AAC.