For:
To me, 7 seems less stable (XP was
rock solid).
My seven is rock solid. my Xp machine is the one blue screening the whole time
Fax console has been replaced by Windows Fax and Scan, which is utter crap, along with the cover page editor.
Not qualified to comment on that
I don't like the transparent program bars.
Then change the theme
Net Limiter 2 doesn't run on 7
But Netlimiter 3 does.
The improvements I was hoping for didn't materialise. (I was hoping to run Office 2010 in 64 bit, but the 64 bit version doesn't support a few of the features that I use. I also wanted to switch from yawcam to the Microsoft software for my webcam, but as it turns out, yawcam is better.)
NQTC
Yesterday, some security guard stopped me from saving a batch file to a program directory.
you can turn that off
I don't know where anything is.
lol, You can make explorer work the same as the xp one, Just forgot how right now.
I don't like having to scroll through the start menu's program folder to find my stuff. I have a 24" screen FFS, let me see all my programs at once.
I don't like the new task bar. I want my task bar shortcuts separated from my running apps. If I've got explorer running, and I want to open another explorer window, I don't want to have to right click to do it.
Middle click then 
Other stuff.
Against:
Installing OSs is like having a marlin hook shoved through your nose. Removing them is like having it ripped out.
Lol
I might not be able to run the latest software (in the future).