Just to test the service, I downloaded songs from Lady Gaga, La Roux, Dire Straits, Merle Haggard, Gordon Lightfoot, and Slowhand (Eric Clapton). According to MP3Tag, the bitrate quality varies from 112 for Dire Straits up to 320 for Eric Clapton.
Some of the choices of songs were slim. Merle only pulled about a dozen results, and about 5 different songs. Of course, the more current/prolific the artist, the more results you'll receive.
As for the legality, I'm not sure. No compensation for the artist usually means something fishy is going on. There is a support link on the bottom of every page, but it is not necessary to donate anything.
After testing the songs, and listening to the downloads, I deleted all of the songs since I already had all of them as part of the original albums at 320 bitrate in another folder on my hard drive.