I was in the first two seasons, and for a few weeks into the fourth season. It's amazingly awsome... but it is very time consuming if that's a concern. I loved it, but didn't have the time to keep up with it regretably. Heh, Jesse Bedlam was on my team over there... that's why I was so strong on debating him this week... I've done it before.
I had a few great matches over there that I loved. I specifically remember when in a match I had Ult. Captain America and someone else had I think Moon Knight, and I had a dog fight with his helecopter and an american jet. I lost that match though
Also, in season 1, a guy named X (haven't seen him around much lately) had the character "The Fury" from the old Captain Britain comics, and for an arc of Uncanny X-Men that was completely unbeatable... and after most the season of being undefeated, I was the first to find a way to defeat him with Cable. Good stuff