The LongHorn installation was really smooth. It now collects all the information it needs (i.e.: Computer Name, Upgrade or New Install, partition, etc.) up front. After that you don't have to do a thing, it installs and reboots all by iteself. I came back an hour later and I was looking at the desktop.
They have a thing called the LongHorn Drivers Supplemental Pack. This is basically a collection of XP drivers that you can rig to work in LongHorn for things like networking, video, etc. It didn't support anything in my system. I installed my XP drivers for my wireless network card and it worked fine. I did all sorts of tricks trying to get my sound card to work but have had no luck yet.
A lot of products detect which operating system is running so they will complain when starting them. So far, I was able to go into the properties and run the application in compatibility mode and it worked.
So what's different? Most noticable the transition and fading effects for every window. The title bar of every window now is transparent. The control panel looks totally different, everything is grouped together even more than it is in XP.
As far as IE7, there didn't seem to be a damn thing different. The buttons at the top were rearranged and looked neater. It did have tabbed browsing, but all of the options menus looked the same.
I have only messed with it a little bit, so I am sure I will have more to report soon.