It's "macro" but minimum focusing distance is 1m and its maximum magnification is 1:3.5. Not knocking it, but I'd say it's more for close-up work than for macro (which I personally think of as a 1:1 magnification). Anyway that's beside the point really, as Sachin is looking for a portraiture lens, not macro (although I'm sure he'd be pleased if that were an added bonus
) (Except I don't consider proper macro to be less than a 1:1 magnification.)
Also the weight of the Sigma is not that much lighter than the Nikkor 70-200mm 2.8 VR lens:
The Sigma weighs 1380g
Nikkor 70-200 VR weighs 1470g
It's worth noting that the Nikkor 70-300 VR weighs 745g - a very comfortable weight indeed
I seriously think it wins on the value for money score as well, if you're on a budget. At Warehouse Express (today):
£1148 for the Nikkor 70-200 2.8 VR
£600 for the Sigma 70-200 2.8 (no vr)
£320 for the Nikkor 70-300 f/4.5-5.6 VR
Anyway more food for thought for Sachin, hopefully