I did try it. Rick and I worked on writing network software.

We found that the person typing contributed somewhat less as they had to deal with syntax issues while the other person had time to think. Overall though it was a very effective programming technique. Rick was very strict about his code and wanted to be the person typing. I didn't think it mattered so I agreed.

The downside came later. My boss slammed me for "bothering Rick" who he claimed was doing excellent work. I tried to explain the idea of pair programming but he ignored me. Rick got an excellent rating and a raise. I got slammed and no raise.

I don't recommend pair programming.