It is slow, but you get crazy mad damage reduction while in the animation. Last night we were flying en masse into primes, pyros, hunters whatever and alternating between biotic charge and heavy melee. The three of us would gang up and put a beat down on a prime without firing a single shot. It was epic.
My favorite guns for him are the reeger, piranha, and wraith all with the omni-blade attachment. Those three shotties are fairly light.