Ive been using Windows Vista for the last 3 years or so, and Ive never had any major problems with it except for occasional adventures with user permissions because I have a reasonably powerful system(2GB RAM, Radeon Graphics, Core 2 Duo). But the slight sluggishness of performance with some applications is always noticeable - which is why Ive been waiting for Windows 7.
Ive just installed the trial version about 10 days ago, and so far I am pretty impressed.
1. Pretty quick install(I did a clean instal) compared to the previous version
2. Very intuitive interface with several enhancements like drag and snap windows and the new toolbar
3. Windows 7 Libraries that make managing data much easier
4. Flexible desktop gadgets which can be moved anywhere on the desktop
5. Easier Wifi management and connectivity
6. BitLocker To Go feature for encryption of data in USB drives
7. Less intrusive system overall with better system tray and user-account-control
8. Productivity enhancements like jump lists, better search and taskbar previews
9. Improvements to Accessories like paint, calculator and new ones like the snipping tool and Network projector connection wizard
10. More user friendly device manager to manage hardware and peripherals