The downside to this is that the store isn't very good at surfacing new content, and by learning users' tastes, it creates a hermetic environment in which users are surrounded only by music they like. The fun of using other stores, such as Apple iTunes or Virgin Digital, is that fresh editorial content and user feedback lead you to new and unexpected things.
AOL Music Now currently offers more than 2 million tracks, with content from all four majors and more than 100 indies; it feels light on indies when compared to the competition, especially Yahoo, which has deals with more than 40,000 indie labels and artists. It doesn't offer gift certificates, an allowance system, parental controls, podcasts, or audiobooks. Editorial content is barely there (it exists only in the form of hot lists), as are community features--you can browse a few users' playlists but only the few that are posted. The service offers more than 80 radio stations, but they're grouped under music-genre pages, not listed altogether on a radio page.
In our testing, searching was easy (the service is kind to misspellings), but browsing within a genre was difficult, since there's no way to see all artists in a genre. Making purchases and downloading subscription tracks required small software helpers, but that worked fine in our testing. The service uses Windows Media Player for downloaded tracks. Our only hassle was that downloaded tracks weren't automatically added to our WMP library.
We hope the browsing interface is a lot more developed by the time AOL Music Now launches in late June, as it's surprisingly bland right now. At the full launch, expect to see purchasable music videos and song sharing with AIM. If you'd like to give it a try, the service currently offers a 30-day trial, which is more generous than most. If you experience problems, AOL has a support link to an automated FAQs list and an e-mail form.