Windows 7 builds upon Windows Vista, bringing together the various technologies and frameworks introduced in that troubled release, and building upon them, exposing them to users in useful manners. HomeGroup, for instance, the technology that makes networking painless, doesn't use any new technologies - it just brings together Vista technology in a useful way.
There are also a lot of interface overhauls in Windows 7. After using 7 since last Christmas, the amount of work Microsoft has poured into the user interface and user experience has become one of my favourite "features". Where Windows Vista was a barrage of colours and weird glossy nonsense, Windows 7 has been toned down and made less eye-piercing, the best example of this being (for me) Windows Explorer. Colours removed, useless widgets dumped, everything streamlined.
The taskbar and Aero Snap and Peek are other interface additions and overhauls. The new taskbar takes some getting used to, but once you're in, you're hooked; the new system tray really helps here. Aero Snap may not seem very useful at first, but wait until you need to work with lots of multiple documents, and you'll start to value being able to 'snap' various scientific articles next to one another easily.
Performance-wise, Windows 7 is also an improvement over Windows Vista, and some benchmarks (for whatever they're worth) even say over Windows XP - which actually doesn't seem too weird seeing how Windows 7 will be able to use modern hardware more efficiently than Windows XP can.
It's not all about roses, of course. The biggest issue with Windows 7 is the massive security hole in the default User Account Control setting. While this issue can easily be resolved by moving the UAC settings up to Vista levels, most people won't actually do that, allowing malware writers to have a field day once Windows 7 gets released.
Today, Microsoft announced that Windows 7 has hit "Release to Manufacturing", meaning the code is finalised, and the operating system is ready to be prepared for shipping. Windows 7 will be released October 22.
There's even a corny video of the Windows team signing the RTM build. Sadly, no footage of Julie Larson-Green in this one.