The value in these is almost entirely in making new contacts, so if you're going make sure to at least make some connections. Most workshops and classes are targeted towards corporate types who don't know shit, don't know if this is any different.
I went to the last one and while I did pick up a couple of nuggets of decent information, I would expect that their idea of "advanced link building" is pretty subjective.
Definitely worth it for the networking and social though.