However disreputable, he was very good at what he did.
Like Lenin.
Yes, Mohammed was clearly good at what he did...attacking basically undefended peoples and subduing them with extreme violence. His tribe was nomadic and had lived at least in part through raiding camel trains bringing merchandise into that part of the world. This was some time after the collapse of the Roman Empire, so what little stability and protection had been granted to the many kingdoms and peoples in that area was long gone and they were just ripe for the taking.
He took the basic Arab business and war model and notched it up to a world-domination model. And most of the time, his attacks were successful.