Attended the one last Friday as a newbie (going on Saturday too) and I highly recommend it to anyone on the fence about going. It's a really fun learning experience, just make sure you give the coaches room to talk and pay attention to advice, and you'll be golden.

The games are surprisingly realistic compared to real 6v6's, it's not just a "noobfest" like some people think it is. Although, you will still have a lot of leeway for errors if you're having trouble understanding the comp format and need help with rollouts, positioning, etc. But, then again, that's what the mixes are for: to help you brush up on those things.