Yes, main reason is because it is faster over the internet than the freeware mentioned here, and because of the integration with Windows in terms of security.
However, VNC works great for me in LAN environments, i.e., speed is as good as pcanywhere, and is very much reliable, plus you don't need to pay licenses like with pcanywhere.
We have a lab with over 50 machines, to pay for 50 pcanywhere licenses wouldn't make a lot of sense.