My sense is that there is a narrow slice of software developers who genuinely do flourish in a pair programming environment. These are people who actually work through their thoughts better with another person in the loop. They get super excited about it and make the common mistake of "if it works for me, it will work for everybody" and shout it from the hilltops.

Then there are the people who program best in a fugue state and the idea of having to constantly break that to transform their thoughts into words and human interaction is anathema.

I say this as someone who just woke up in the wee hours of the morning when nobody else is around so I can get some work done (:

I worked for five years at a shop where a few years in we started pair programming aggressively. One of our most experienced engineers was really into XP and agile work (in the “purer” meaning of the term). He often suggested pairing when thorny problems came up, and eventually it spread. It often took half or more of the available time for programming each day. That was by far the best working environment I’ve been in. The team was excellent and it seems like we all improved in our skills when we started doing it more. We cut down on how long it took to get in while managing to produce better code. It made planning features and adjusting to unforeseen snags in plans so much quicker. I can’t emphasize enough how much of an impact it made on me as a developer or how much I miss it.

The biggest downside to me was that it forces a level of engagement exceeding the most heads down solo work I’ve done. I’d come home and feel mentally exhausted in a way I didn’t usually.

I like pair programming for certain problems: things that are genuinely hard / pushing the boundaries of both participants knowledge and abilities. In those scenarios sometimes two minds can fill in each other's gaps much more efficiently than either can work alone.

I like pair programming. Not everytime or even everyday, but to shadow a junior a few hours a week, or to work with another senior on a complex/new subject? It's fine.