pros:
*The modern UI is pretty cool. it takes 5 to 10 minutes to understand how the damn thing works, and once ur past that, you can do everything in Windows 8 that you could in windows 7.
*It feels somewhat faster and more responsive than Windows 7. Startups and shutdowns are definitely faster.
*A Microsoft account keeps all your Windows 8 computers in sync. You log-in to all your Windows 8 devices using a single user profile that's stored in the cloud.
*Live tiles at first might look like Windows 7 (vista sidebar) gadgets showing live feeds from the internet, but they are more than that. Clicking on them launches full-screen modern UI apps, which you'd either love, or hate. I love them.
*I've heard rumors that Windows 8 is more resistant to malware compared to Windows 7. I'm not sure if that's true, because to be honest I've never had an infection on a Windows 7 computer, neither on a Vista. Last time I remember a virus, was when I was in junior high surfing something obscene on a Windows XP system running the terrible "PC Tools Free Antivirus".
cons:
*No Start button. Not much of a con, because the new start screen more than compensates for the missing start orb, and there are 3rd party alternative start button apps available for download all over the internet. But I for one, have not installed any of those. The start screen is good for me.
*Weird multitasking implementation while working with modern UI apps. Of course you can switch to the desktop mode and enjoy the traditional windows multiprogramming facilities you've always had, but if you want to run lots of modern UI apps at the same time, it can get pretty annoying. Not that you can't, of course you can. But it feels weird. Maybe it's just me.
*No Aero. This is the one thing I really dislike about Windows 8. When you are on the desktop, all the Windows 7 (Vista) Aero effects are gone. No 3D glass effects, no 3D flip, and flat ugly window borders with sharp unrounded edges. I've heard of people who dislike Aero. But I'm not one of them. I miss Aero.
Overall, it's not a complete waste. There are things about Windows 8 you'd come to like. In fact, I'm typing this on Windows 8. It's not as bad as some people describe it. But the UI changes seem to be all geared towards a touch based device. It works perfectly ok with a mouse and a keyboard, you can still do everything you want to do, but on a traditional computer without a touch screen, it feels a little awkward. You'd get used to it though, and over time, you'd stop missing Windows 7. Of course, all this is my personal opinion. Your experience might be something entirely different. So if I were you, I would try it myself for a day or two before agreeing with things I read on the internet. Good luck.