I just completed it as a duo (Arc Titan and Void Hunter) and it was a blast. Not sure how it would play with a full six stack but it kept us on our toes the whole time with just two. Lots of close calls, almost wipes, and we whittled the boss down using basically nothing but our supers. The constant ads spawning in the boss room is intense and the waves get harder and harder as the fight goes on. It's terrific!