I’ve had a few recurring issues with it. When you fill up your 20,000 songs, you obviously will have to delete some to make room, which is fine, but when I delete some from my collection it doesn’t recognize this and will never let me upload those songs again until I create a new folder called something different and drag and drop again. Even though it doesn’t always work and has to be restarted, and even then it still doesn’t work sometimes. Some albums it just will not upload every song from, no matter what I do.
I’d like to have a web based option at some point, especially considering how web based Google likes to do things, it makes more sense for them to do it that way.