I use youtube for music on a computer fine, all the songs I stumble upon the playlists are usually a bit crap and normally just user created ones. Its annoying having to load the video too, normally just some crap slideshow someone put together. I know you can get it with the screen of with fiddling on an iphone/ipad, don't think it works natively on android.
You can download albums with prime, im on the tube a lot, even though i have virgin Wifi on the underground its nice having some albums that i don't have to stream. But to be fair it have an ipod for any music i want
Also tried out the instant video download the other day on a long train journey. Very handy as i never have a constant connection on that train ride. It worked ok, wished the quality was a bit higher, looked around 720p to me. It was also quite strange how it buffered slightly at some point even though it was downloaded, i had a feeling this might have something to do with the Xray overlay with information of the actors in the scene, which is a nice feature. Once i exited it and reopened it it was fine. I watched a new pilot called sneaky Pete, rather good, i recommend it.
Big fan of the original series on Amazon also, My mums a big Ripper street fan so i share my prime with her so she can watch them fanny about. Watched black sails also, they put a fair bit of dough behind their productions.
Apart from their tax avoiding shenanigans, I can't rate Amazon any Higher.