We just joined this summer. I feel like it was worth it. Make sure you use an offer that gives you at least 5 movies up front and no more than 4 to buy later at regular price. There are a few variations of the initial offer, so shop around if necessary to get the most from your money. Also, take advantage of the offer to get 1 movie toward your required purchase at at discount when you place your sign up order.
The regular price movies are about $22 for a standard dvd, many older titles are much less (but won't count toward your required purchase) and you will have to pay shipping which adds a few $. They often run specials on movies. They just had a buy one get one 50% off sale. Now it's buy 2 get 25% off total order... Supposedly once you buy the required number of regular price movies, they offer more incentives to stay with the club.
We figured we would buy the movies anyway, so it was worth it to us.