It is absolutely worth it to me. I split the membership with my sister, so we are both able to enjoy the benefits of free 2-day shipping on nearly anything we could possibly want. That in itself has saved us a ton of money. I am primarily the only one who uses prime tv streaming and music streaming. I have not yet looked into the book library as my Kindle died a few months ago.
If you shop at Amazon a lot then Amazon Prime is the way to go. It really doesn't take too long for it to pay for itself. It is well worth the upgrade. I have never had a problem with it and I have always been pleased with the service and delivery.
I definitely recommend it! Even if you don't use their shipping services too often, you still have access to lots of movies and TV shows. And when you do need to buy something, you won't have to worry about shipping!
I have to say, if I did watch a lot of movies/TV series or wanted to get music from Amazon and did a lot of shopping on there, I'd consider it a fantastic offer. But the only thing I do on Amazon is buy eBooks. So in my opinion, I they're really missing a trick not offering some of these things as stand alone services.