I have been a member for about 3 years. So far I have enjoyed it. And like Mouser said, once you fulfill the first year's obligation, technically you can remain a member and never have to buy another movie from them again if you don't want to. I also use it to get some older movies, and buy new releases elsewhere. Being VIP gives you better deals. Obviously it makes more sense to go buy a movie at a store instead of through the club if you are only getting one movie. Most movies after shipping are around 26 dollars. You can find them much cheaper in the stores. So make sure you take advantage of any deals they offer once you fulfill your membership obligation.
Actually today was the first day I did not like being in it because I accidentally forget reply to the featured title and they automatically charged my credit card and sent me a movie I already have. I realize I can return it, but paying money to return something I never wanted kind of irks me. But I suppose this was my own fault.
My advice is to just stay on top of replying to those featured titles to avoid this happening.