gethan - 1:48 pm on Apr 21, 2010 (gmt 0)
They make major changes, what, a couple times a year?
Maybe 4 times yearly something changes with the UI that the majority of users see.
On the facebook API, pages, groups or introducing things such as beacon, facebook connect etc etc - much more often. First hand experience developing with the facebook API I've found changes are so frequent that something breaks every month or two.
I do agree with that the UI is simple and elegant - and that it is a big part of it's success compared to myspace and other social networks.