Club membership gets you a free figure, either 3.75" or 12", 12 months of the Club newsletter, free listings on mcax.com (now online), access to the forums, and paid member pricing on all items in the store.
I've always gotten the 12" member figure in the past so that, along with the newsletter, is worth the price IMO. It's debatable if the magazine is worth it or not. Personally, I like it, but there are a lot of people that complain about it not having the kind of conent that they want to read about. Mcax.com, I haven't used that yet as it just came on, but it is a sales alternative to eBay, Craigslist and forum postings. It remains to be seen if that's a worthy perk.
I think it's a way better deal than the Gentle Giant Premier Guild, for example, because you get one bust and a ****-ton of headache for your $60 (plus shipping) with that subscription.