I am a GANG member, and have been, for a couple of years, but I'm going to let my membership lapse.
Here's another article that brings up a lot of relevant issues with why GANG has kind of failed its membership, in a lot of ways. My experience has been that the #1 biggest "perk" that you're given for membership is access to the members-only forum; but it's extremely inactive and most of the professionals that would be willing to help the kind of person looking for that kind of communication have moved on to other social media. Additionally, a lot of the industry-related perks, like cheaper tickets to events or registration to conferences, occur on the west coast. I did my best to be involved with GANG, and I felt like the leaders of the organization didn't care much about outreach, educating people, or representing their interests in the gaming industry, which are all variously claimed as the purpose for the organization.
Additionally, as highlighted in the article I posted, they've become increasingly insensitive to the community they're supposedly supporting. The videos they showed during the awards ceremony were frankly insulting, including one that outright bashed Destiny for a good 3 minutes. Regardless of what you have to say about the game, I spoke to a friend of mine who is a sound designer at Microsoft, and he was practically shaking because he was so upset by it.
That's not to say there are no good people in GANG. Ultimately, I think everyone that's running the organization means well, however the two most active members with the most positive vision of what GANG could be (Tommy Tallarico and George Sanger) haven't been very involved in recent years. My experience is that the organization means well, but is out of touch and doesn't offer any real benefit to members who aren't already established in the field, or in LA/SF/Seattle, and there's not much drive to change that.
On the other hand, GDC is an absolutely wonderful experience, and I really recommend you go if you're able-- the audio pass is expensive, but much less so than the main conference pass, and you would still have plenty to do for pretty much every hour of the conference. The Audio Bootcamp day (usually Tuesday) is basically one whole day devoted to informational sessions, and it's absolutely worth going to once, at minimum. Every time I've gone, I've found the game audio community there to be extremely friendly and supportive, and I always learn a ton.