Rdio, the popular internet-based streaming music service, now has an app for Macs. It’s free for subscribers and it’s an excellent alternative to using their site.I’ve been a Rdio subscriber for a few months now and I really like the service. It’s $5 a month for the ability to listen to an unlimited amount of music on your computer and $10 if you want to be able to listen on your mobile and sync your phone with music as well. It’s a great deal for me because I get access to a huge selection of music, it keeps me in touch with newer music, and it save me money on buying albums. I tend to listen to podcasts when I’m on the go, so the cheaper plan is ideal.Rdio’s site is an OK, but not great, way to use the service. You need to have Flash running to play the music and since I tend to use it in a lot of short bursts I always have a dedicated browser window open for it. Aside from it being on the web and subject to unavoidable issues like browser crashes and internet connectivity, the site doesn’t handle keyboard controls and has no interaction with the OS. By moving to an application, Rdio enables both of these, plus it handles your Rdio downloads and there is a new Match Collection feature.The Mac app (in case you are checking, it’s not available from the Mac App Store) basically carries over the UI of the site, but with some improvements. Your queue is moved to the top, as opposed to the left side and the controls (volume, play/pause, etc.) are even more prominent. Page load times are about the same, but you tend to get more useful information on the page, and less cruft. The song controls (add to queue/collection/playlist, download song) are all there in the familiar “+” drop down and you also get the chance to see activity information about the popularity of an artist, track, or album.The biggest single improvement with the app is the use of Growl notifications. When a new song starts playing you’ll get a familiar notification window that tells you the artist and track names. This is a great feature–it gives a bit of information about your music without taking you away from what you are doing. The feature can be turned off using your Growl controls.Being a good Mac app there are a lot of keyboard commands available. You can pause, go next/back, or control pages with commands like home, forward, back and reload. Rdio does not work with iPhone-compatible headsets, so if you are using one you’ll be able to adjust the computer’s volume but not change/pause tracks.The other feature that makes the app attractive is Match Collection. This will scan your iTunes music collection “to see which music from your iTunes Library is in Rdio’s catalog.” It won’t transfer files to or from your computer, it will just scan for information so that Rdio knows what you’ve been listening to. When I tested this on the limited music collection on my Mac never completed. For some reason it just scanned and scanned until I had to force quit.Customizations and preferences are very limited right now. You can basically disable iTunes keyboard controls (so that the Rdio app is used), keep the Rdio mini player on top of all your other windows, and keep Rdio in all your Spaces.It seems like the developers are still working out some kinks. My Match Collection feature doesn’t work and when I try to upgrade (from 1.02 to 1.03) the new version downloads but I get an error extracting the archive. Those are relatively minor though and I do consider the app a better way to use Rdio.If you are a Rdio subscriber I’d recommend giving the app a try. If you aren’t and are looking for subscription service, Rdio offers a free week trial, it’s probably worth checking out.