Can you elaborate?
So much smoother, never needs a reboot, the UI is just amazing, new taskbar where shortcuts integrate with running programs is a godsend,running cursor over icon in taskbar shows all open windows in that program, themes like a slideshow as your desktop,wiggling a window closes all other open windows to minimise, dragging a window to left or right side of the screen will cause the window to fill that half of the screen, new search feature that finds any file instantaneously, can tune it so you never get pestered by popups....ever,homegroup allows piss easy setup of network PC's,far less memory hungry than vista, x64 version runs 32 bit apps flawlessly while allowing you to use more than 4GB of memory,native support for touch screens, amazing support for streaming to you from home PC say to your ipod touch while out and about,media centre included is amazing considering its built in and from Microsoft, Windows explorer is great now....completely redesigned and tons more shit I'm probably forgetting.Basically its just so fucking smooth and easy to get things done, you'll wonder how you stuck with xp for so long.
Main thing it just works for 99.9% of people right off the bat, most drivers are included on the install disk so your up and running within 20 mins from formatting and doing a fresh install (no other way IMHO).