I was just coming here to post about this very thing. I've been in the GCU all year and it pretty much guarantees I buy all my games from BB. For new releases, you're talking $48+tax vs the normal $60+tax. But it doesn't just work on new releases, as mentioned it will work on any new games even those on sale. And yes, that includes the upcoming Black Friday sale. If you buy new games at all this is a no-brainer. You will easily make your $30 back (and then some!) over the course of 2 years.
Heck, I think I'm gonna pickup Lords of the Fallen & go ahead and add 2 more years to my membership at that price.