Yeah, I did the co-cop with my girlfriend, who isn't typically a gamer, and the "JAM X!" threw her off. We had to switch controllers so she sniped the boss while I jammed X.

It's a decent final boss, though. Better than in RE4, which I thought was kind of jumbled. I wish they had put together the phases in the boss fight a little better, though, because I would run and do the boulder thing first, the boss would jump to Sheva, and I would keep trying to cross on the boulder to help her up.