It's kind of neutral for me, except for early beta releases of major upgrades - that post-Keynote thrill of checking out all the recently-hyped features. But all the interim betas of dot releases? The thrill is gone. Just another brick in the wall.
Different reactions for different people. It's similar to cleaning the house. There are those who get a sense of accomplishment - an enjoyment of their newly-clean environment. For others, it's just a chore. Although, come to think of it, there is a bit of a thrill when finally cleaning those little corners I miss during the daily routine - it's easier to see what I've just accomplished.