Pietro is a wonderful guy. I took two upper div classes with him and worked in his lab, and I can say that he is both an excellent teacher and a mentor. His class is very entertaining and he took one of the hardest subjects in physics (E&M) and actually made it doable. He spent the most time focusing on the useful aspects of the material and ignored the unimportant stuff. It was refreshing to have a young and energetic professor for what are typically thought of as the hardest upper div physics classes.
Working for him has been great as well. PBPL (Particle Beam Physics Lab) is a fun lab with a bunch of great people. To any physics students out there looking for a good research opportunity, there seems to be funding, and PBPL is a great place to work.