Blessing or folly? The cornerstone of the new Napster 3.0 is the online music store's all-you-can-stream Napster-to-Go service. It's already finding plenty of detractors, but we think it's an exciting change in the online music business. For $14.95 per month—about the price of a CD—you can download all the music you want and transfer it to a portable player so you can play it without being tethered to your PC or the Internet. Napster now has well over a million tracks in its catalog, with roughly 90 percent available to Napster-to-Go. The downside is that you won't own any of it.

All-you-can-stream services are nothing new—both Napster and Musicmatch already had $10-per-month streaming plans in place—but what is new is the ability to transfer downloads to a portable player. Actually, you can carry them on up to three portables and play them on three desktop PCs. There are steep requirements, though: The desktops need to run Microsoft Windows XP, and the portables need to use Microsoft's Janus DRM technology for subscription content (look for a "Works with Napster to Go" logo on the box).

Currently, only eight devices meet the standard. That means you can't use Napster-to-Go with iPods or most other players on the market. Fortunately it does work with some very good players, including the Creative Zen Micro, the Dell Pocket DJ, the Gateway MP3 Photo Jukebox, and the iRiver H320. You may need a firmware update to make these work with the service.

How you'll feel about Napster-to-Go depends on how you feel about renting music. The service lets you download an unlimited number of songs, although you can't burn them to CD and they'll expire once you stop paying the monthly fee. Critics complain that at the end of a year you'll have spent $180 and won't own a single song. That's true, but people using NetFlix don't get to keep the movies they watch. Napster-to-Go is for people who want to enjoy a variety of songs, but aren't interested in building a collection—which would ultimately cost a lot more if you had to buy each song.

Being able to download anything you want is really a lot of fun, and means you can take a chance on lesser-known artists without worrying about the usual 99-cents-a-pop cost of buying a track. We found the Napster catalog just as strong as Musicmatch's (the other leader in the non-Apple music world) in bestsellers. Both had 17 out of 20 albums from the current Billboard chart, but Musicmatch was far stronger with artists from critics' best-of-the-year lists.

Aside from Napster to Go, there isn't a whole lot new in Napster 3.0. We were surprised that Napster hadn't refined its interface for this release. Moving through pages and selecting album content is far easier with Musicmatch, and its search tool is forgiving of misspellings, while Napster's isn't. In other ways, Napster provides a more enjoyable user experience than Musicmatch or the iTunes Music Store, though: With opinionated user forums, articles written by industry experts, and prebuilt playlists, it gives users more ways to discover new artists.

Napster-to-Go's very specific requirements will keep many from trying the service, but we think those who do will quickly warm to the idea of renting songs. With this many to choose from, the service is easy to love.