When they eventually enter service and I get my first ride on one, I'll certainly notice the difference! It won't be quite as stark a change as it no doubt was when the stock was replaced the first time around of course, but I'd be lying if I said there won't be noticeable differences between the Met-Cams and the Stadlers from the passengers' perspective.
The fact that the last stock replacement was part and parcel of a system-wide refurbishment/rebuild that totally transformed the look and feel of the system no doubt has something to do with this perception. What doesn't help is that the 'ongoing' station refurbishment programme seems to have stalled out, leaving quite a few stations across the system looking, for lack of a better word, unfinished at platform level. Obviously, nowhere near as bad as the system was in the last few years leading up to it's May 1977 closure, but not all that great either.