Pretty neat! I am curious about your triangle count. This guy would make a good base model...though I'd get rid of the spikes. Let the gear you put on him take care of those details. You texture map is pretty weak, but I'm guessing you didn't put much time into it. I'd say you're on the right track if you are new to the software.
It's a pretty normal result for a first timer, my advice to you is to look around for a good tutorial (series) on character dev in mudbox. A good tutorial can radically accelerate the learning process for you by showing what works and looks good straight away instead of you trying to find out by yourself by trial and error.