I've always been off and on with him. As mentioned above, he's a big guy with big impact moves that can be fun to watch. Hard clotheslines, press slams, power slams, tossing people around like rag dolls, grabbing people by the throat while they're on their back and then slamming the back of their head back down to the mat, his cool finisher, etc.
But at the same time, he just lacks the same aura and "oomph" that other big guys have or had that made them more interesting to watch. Goldberg, Kevin Nash, Mark Henry, Big Show (especially back in his Giant days in WCW), Kane, etc. The fact that WWE has booked him on a losing streak as soon as he moved out of the "squashing jobbers phase" certainly doesn't help him at all.