Explorer not expanding folders as you "explore" your hard drive
easy fix, go to "Folder Options" and there's two new options down the bottom, one of them is to expand folders automatically, check it, no longer a problem.
Why Microsoft changed how explorer functions in that regard after all these years I really don't know, but at least you can put it back.
And if you want to connect to an SMB share (for instance on a Mac) you'll need to go into Local Security Policy and change the Lan Manager settings to accept NTLMv1 passwords as well as V2.
I'm about to install 7 on the last of our computers here (it's on my desktop and laptop, about to put it on the wife's laptop) and I'm really liking the "Homegroup" feature, no longer will I have to share random folders so my wife can see our family photos from her computer!