This is something I've never understood. Yeah, the registry is a nightmare if you have to fiddle around there, but the taskbar? My god, the Windows 7 taskbar is the paragon of desktop computing perfection. It consolidates a launcher, window switcher, search, explorer, notification tray, and clock/calendar into one convenient bar that certainly nevers feels crammed. Microsoft knocked it out of the park with the taskbar. Oh, and Aero snap is cool, too (I know, there are OS X alternatives).

I should also add that Lion does not manage memory well. Opening a new tab in Chrome is a beachball party waiting to happen.