He mostly claims other people's work for himself. I suppose he's a good salesman and a good huckster, that much is demonstrably true. He's also apparently competent as a mathematician somewhat, but it's doubtful how much of Mathematica really is his own work. He puts everything under his own name and sues anyone who disputes otherwise.

I wouldn't agree with any of those characterizations. I see him mention the team he has built and what they accomplish together rather frequently.