I've only used this once, but the website is pretty legit. They even have a Terms and Conditions which they suggest you read before using the website and are pretty strict about the terms under which you can use the website. According to the Terms and Conditions, "The Content, with the exception of User Submissions and Third Party Content, including text, graphical images, photographs, music, video, software, scripts and trademarks, service marks and logos contained therein (collectively "Proprietary Materials"), are owned by and/or licensed to us."
Overall, I would say it seems like a good website. I do not know too much about the music selection, but the website itself appears to be pretty safe.