I've had a 920 since it launched in 2012 and learned to really like the capacitive buttons. I heard that the new 950 would have on screen buttons and I was sure that I would hate them. Two weeks ago I got a 640 with on screen buttons and I would say that I am learning to actually prefer them. For one, they seem to work just as well as the capacitive buttons on the 920. Secondly, they dim along with the rest of the screen so they are not too bright at night. And, finally, I can hide them when I am watching video or viewing photos.
I was highly skeptical, but now I am sold on on-screen buttons.