I have been trying it out for a couple of days, and it's too buggy. Starts downloading things when there's nothing to download, sometimes it skips and stops even though connection is strong (I tried Spotify and that wouldn't skip,switched back to Apple and it skips).
The service itself and the app design isn't as bad. Sure, it's different and it might take some getting used to, but it's not terrible. I just hope they'd work out the kinks a lot faster.
Also, no web player and so far not compatible with Tablets, so Spotify is still my go-to service, although I might give YouTube Red a go after the three months of Apple are done.