I've been a member for around 4 or 5 years now and live in Germany but used to travel regularly to Los Angeles for business.
From my experience they do offer some great events (or at least did, last one I attended was at TODD AO in Santa Monica in 2008 or 2009 I think, no idea about more recent ones) and it does connect you with people but most of these are local to the greater L.A. area. Does this help with a career in in the game industry? Everything is possible, it definitely won't hurt.
If you live in the US or better, L.A. and if the GANG website gets fixed (it's been buggy for months now, no logins/signups possible) then yes, I think it's absolutely worth it but if you're from oversees and don't travel to the US regularly then no, not worth it until at the very least the website gets fixed.