Well, I installed it on one of my older laptops. It's a little faster. The clear type text makes it look a little sloppier. The UI is completely different. It took me awhile to find the "start" command.
It's the opposite for me. I've actually read quite a number of positive Win 8 reviews. There ARE cons, don't get me wrong, but most of the people I've read reviews from have all said they like the direction MS is taking the Windows OS. I guess it all depends on preference.
Besides, as with most things...you can't please everyone. Microsoft decided to reinvent Windows; now x-amount of people "hate" the new UI, y-amount love it. If MS decided to keep the classic UI, I bet x-amount of people would be complaining about how the design of Windows has become stagnant, and y-amount still eat it all up (just look at Apple's iOS).
There will always be people that will complain about change, and there will also always be people that will complain about non-change. Guess that's just the way the cookie crumbles. lol