You've gotta see him in action; he gives great talks. Here's a recording of his SETI talk on the discovery of Styx and Kerberos: https://www.youtube.com/watch?v=u6t51YPOuSA (I worked on Uranus' moon Mab, which is mentioned at the start of the talk).

If you get the chance to see him live, I'd definitely recommend it. Unfortunately, he's very busy, so even during my PhD I haven't had many chances to sit down with him.

The coolest thing to me is that Mark is a dynamicist actually, but has such a deep understanding of instrumentation and image processing that he can attack new discoveries from both sides. Good example of why it serves to have many tools in your toolbox.