I've had Prime shipping for 3-4 years, don't remember which, but I love it! I buy a lot from Amazon so it's worth it.
I really think that Prime is the way to go if you do order quite a bit from Amazon. The 2 day shipping is really great and I just expect it now. If you don't order from Amazon but from a supported vendor, then the shipping is standard and that's fine. I always try and use Amazon because of the shipping.
I've heard of some people sharing the cost with friends but I have a little problem with that personally. The rules say "household member". I share it with family which they appreciate but I pay for it. I think that's better. I think if enough people abuse the rules then Amazon may drop the service and I know I would suffer for that.