I have had amazon prime for a long time now. I still use netflix for streaming. If and when Amazon starts letting me browse movies and save them to a que I'll switch over assuming the content is similar.
I just checked them out to see if they had a good selection and what not. I was really impressed with the variety. I started writing some good things about them in this thread until I noticed something. Just because they have the videos "on demand", that doesn't mean you can watch it under the Prime account. Check out the screenshot below. If the episode does not have a check mark, you won't be able to watch it - without the check mark, you would have to buy the episode. And looking through the catalog, it appears that not a whole lot is available to watch under the Prime account. I was actually considering joining up until I noticed that. I would have been ticked off if I bought a membership thinking I had this huge collection of media to watch and then found out the majority of it was not available.