I loved the Avengers theme but the gameplay did little for me. I'm not a fan of some of the shots or the feel of the machine in genearal. I played it on location a few times so take it how you want. That being said, The Avengers is a dream theme for me. The game just didn't grab me.
I feel like Metallica wins in most categories. Even if you are not a big fan of the band I'm sure MET would be a better game for you in the long run.