People who like it:
Salesmen
People who just surf and use a word processor
People who think eye candy is more important that actually using the PC.
Wrong. I'm a happy Vista user since the end of 2006. I've been using XP before for years and was equally happy with it. But as I'm an early adopter I just couldn't resist Vista (I got if free via MSDNAA). There has not been a single day of regret. The PC runs 24/7 and it is used as a web server, FTP server, SSH server and audio streaming server. Furthermore I use it for programming, image editing, multimedia, as a DAW and gaming system. I wouldn't exactly call that lightweight usage.
Actually it's the "people who just surf and use a word processor" who might not see the benefits of Vista like better multicore support, a better audio system including per-application volume and 32-bit floating point mixing, DirectX 10 (not now but in one to two years this will be mandatory for gamers), a much better security system (if you know what you're doing an UAC prompt is a rare thing to see), a better copy/move/delete dialog that allows you to skip problematic files, keeping multiple versions of the same file and a function that resets your graphics card in case of an error that would lead to a system lockup in XP.
For me, Vista has many advantages and simply no disadvantages. It might be a bit more resource-hungry (but don't confuse free memory in an idle state with memory available to applications when they really need it!) but that has been the case with every new OS. Compare Windows 3.1 to Windows 95 to Windows 98 to Windows 2000 to Windows XP. It has always been the same debate and it's quite tiresome after all these years.