I didn’t have it for long, but i didn’t see anything really wrong with it.

Why do people dislike it so much?

the answer is by Jerry :
My Opinion:

Microsoft rushed it to market much like they did ME. It was to bridge the gap between Windows XP and Windows 7. VISTA was designed to give Microsoft time to get Windows 7 ready. Sort of a Beta version of Windows 7. It was buggy and had lots of coding errors. Service pack 1, and later Service Pack 2 fixed most of those errors and it is now a good system.

It was a resource hog, may people put in on a computer designed for Older OS without upgrading the memory. So it was slow and bulky. If you remember Windows XP was initially designed to work on 125K of memory with 256K recommended. VISTA needed much more.

But it picked up a bad reputation before SP 1 could be released, and computers manufactures started putting more memory into the computers.

Windows 7 is based on the VISTA design with the bugs fixed.