Is pair programming a viable method?
Yes. This is a viable method. In our small (8 people) company we are using pair programming almost every day. But... it is not so easy as I thought at the beginning.1. I think it is almost impossible to work in pair whole day (I cannot explain this very precisely, but when I work in pair I also need some loneliness from time to time, just to take a breath). For me 6h is max.
2. Working in pair is very tiring. After whole day of pair programming I am usually not in the mood for parties ;-) I just want to go to sleep.
3. Not always two people make good pair for particular task. It can be a problem for me to say "no" to colleague from the team if I don't feel we are right pair for the task.
4. I need several days to get used to new colleague. Usually, at the beginning, mostly one person writes the code and we switch rarely. We need some time to learn how to switch roles often and in the way, that we are "equal" parts of pair (i.e. 50% of time coding, 50% of time helping).
5. Some tasks I prefer to do alone. This includes very simple, but arduous tasks (it's faster then), but also tasks I know I am the best expert in the team (then I have more fun because I don't have to answer all those questions :)
6. It is a problem for me to find balance between being a teacher and student. In theory in the second case above I should work in pair with my colleagues to teach them ("exchange knowledge"). And I do. My colleagues also do this with me. But not always, it's very hard to be a teacher or even a student all the time. I think we usually avoid situations "teacher-student". They are rather exception, than a rule. But we keep in mind, that... "today you teach me A, tomorrow I'll teach you B".
1. Knowlegde exchange is unbelievable. Even though we don't work in pairs all the time. Even though we don't like teach/learn all the time.
2. I believe hard/complex tasks are done faster in pair vs. single.
3. I believe, that the code we produce in pairs is better, especially in terms of maintainability.
4. Two heads sometimes make up amazing, surprisingly good solutions (creativity!)
5. I like it, I learn a lot from other guys (and I hope vice-versa :)
Some problems I know:
1. It is very hard to prove, that working in pairs is better than single work. There is several research papers about it, bit the conclusions are contradictory, or at least - "fuzzy".
2. I think that in usual case (task not very complex) this is simply not true, that pair programming is more effective. I belive, that is better from other reasons (better code, knowledge sharing and fun).
In our city several compannies claims to use pair programming in some projects. This includes Sabre (which is Agile-based, so nothing surprising) and... Motorola! AFAIK it is still very, very rare practice.