I just installed the 40's and as a dual monitor user it has been a frustrating experience so far. It decided to change which monitor was physically #1 and #2 ...without me changing where I plug them in on the card. *edit* Ultramon support was swift, got my taskbar moved easily...just had to unlock it ) *end edit* Mind you this is also my first driver change since going dual, so take it with a grain of salt.
3dmark score went up from 10100 to 10770. (GF4 Ti4400 on an AthlonXP1900+ w/ 512mb DDR) ...but I don't care about benchmarks much. So no, I too did not hear about this and instantly think 'w00t, radeon9700 killer!'
My Quake3 timedemo scores actually went down by 20-30fps from 165-177 to a solid 145 in 1280x1024 highest settings, which I care about more. (trickjumping ) I'm curious if it helps JKII and SoF2, though.
Also I noticed a few small glitches, like in Dragothic someone mentioned but also a quick one in nature and Q3 as well. It also moved some of my windows (although this may be due to my use of ultramon) above my monitor so I had to switch to 1920x1440 to pull a window back down into reach. Another dual monitor thing...during 3dmark's res changes on my primary, my secondary flickered to black for a second almost every time, minor annoyance but noting for dual monitor users as it will get old.
The one plus is that I noticed WinXP Pro boot up a lot faster than on the 29.42's (which is what I was using previous to these and seemed oddly slow at bootup) ... a guildmate of mine also noticed this.
Those are my thoughts, I'm reverting to the 29.42's or maybe I'll try the 30's. It's a shame, since the new control panel is slick and nView 2.0 is great for dual monitor users. I'll wait until the next release.