Fantastic! Even for low spec systems.
I was playing this game on my old pc (cos' it's in my bedroom :P) which is a minimum spec system with the exception of a 80GB hard drive with approx. 65GB free, about 4-6 years old running Windows XP Home. It played great! No freezing, no lag, no crashes, ever since first install.
No software or hardware probelms what so ever. And that is on the minimum spec old pc! Played Great on my new High spec PC.
The only downside I would say are the controls - they're a bit hard to get used to - movement in looking and turning around with the mouse although I found it fine after 2 days.