Well, just upgraded mine and am VERY happy.
I think the B&W menu is a definite upgrade in comparison to the old pink/grey one (which I never liked).
Sitting in my lounge, I took a whole lot of test shots of things I normally shoot when Im messing around. Looked at the new ones and thought 'these look sharper'. I didn't believe it and just thought I was was suffering from 'upgrade disease', so I compared them back to older pics of the same things and sure enough, there is a seriously noticeable difference in sharpness.
Im actually now seeming to be getting the sort of results out of my 2nd-hand 80-200 (2-touch) that I had originally expected. I was always quite disappointed with it and actually thought that maybe I had a duff one. Just nothing ever seemed very sharp, always soft.
To tell the truth, the camera has never seemed particularly sharp in general to me. I was always wondering if I had the infamous back-focus issue and just looking at a couple of my old shots, it does kinda look that way. Be interesting to see what I get with my other lenses.
To give you a quantitative difference without posting examples (I can if anyone is interested), in NC, the new pics are SHARPER with sharpening turned OFF than the old pics are with sharpening set at HIGHEST.
Before anyone says, Ive had a look at the EXIFs and the settings are all pretty much the same, bar that I was using Aperture Priority this evening rather than Auto when I did my last lot of similar shots. (AF-S, Single, generally centred). I just wish I had done a few test shots before upgrading the firmware.
The only other thing is that I took my original shots not long after getting the lens and so was fairly new to it at the time. However, at the time, I felt that I was getting better results out of my 70-210 f4-5.6 than I was out of the 80-200.
Other than that, the AF lock-on in low light seems better (thats all Ive done so far). It seems faster to lock on, with less hunting and more definite about locking on when it gets there. It often used to just sit there thinking about things when it was basically in focus, but not actually moving the lens. Now it just stops moving the lens and beeps. I do think the beep has changed slightly, but who knows
So, all in all, it might just be 'upgrade-itis' but I think its definitely better in the AF dept.