To me it's worth it because I attend the convention every year, and I pretty much get the membership by default.
The newsletters are kind of cool for Sigma 6 fans, because they often have news and information about Sigma 6 before you can get it other places, but beyond that, they're not all that great.
The free figure (yes there is a free figure with membership) is hit or miss. I liked the Nullifier figure this year, but they haven't been all that great in years past.
There are also discounts in the Club shop as well.
When it comes down to it, yeah, it's definitely worth it to me, but your mileage may vary...
Justin