I like Vevo, it gives YouTube music videos back, but sadly it comes at a price and a big one at that.
Great quality videos and sound quality, and all at the touch of a button, and now an app for the iPhone makes things better (not available in the UK) and play well, and the comments of the videos are in general very positive.
My only niggle is advertising. On most videos before playing, there is an advert. Usually for 30 seconds, with being able to skip most after 5 seconds, which in my view is totally unacceptable. Yes, YouTube has to get money from somewhere, but this isnt the solution and are driving their userbase away to other alternatives without adverts. Its their loss, sadly.
Overall, good quality videos, but the advertising gets obesssive.