Despite what many Microsoft/Windows sceptics would have you believe, Windows 8 REALLY isn't an evil OS designed to make life difficult for PC users in favour of the tablet market.
Microsoft seems to have cut out a tonne of crap from previous versions to improve performance in Win 8. A good example is the desktop; windows now have a solid-colour border similar to XP, rather than wasting resources rendering translucency and shadows everywhere. Only the taskbar is still translucent Win 7 style.
The super-speedy boot time is really convenient, too. My laptop boots faster than my phone, for goodness' sake!
In terms of real performance... I can browse the web very smoothly, use Maya and GIMP without a hitch, play PotC pretty well... the list goes on.
Using a PDF as an example, I can open an 82 MB file with over 100 pages in a few seconds with the Reader app.
Obviously I can't say how either mine or my dad's laptop will perform in two or three years' time, but it's looking good so far.
One thing I will say is that, on a laptop, Windows 8 is much quicker to navigate with a touchpad supporting gestures (such as swipes, two fingered pinch/zoom etc).
If yours doesn't have that functionality already, I think you can download drivers which enable gestures for your touchpad.
It's not compulsory, just more convenient if you don't use a mouse.