Buying Traffic

Ive never done it myself but i see there are site who offer massive traffic for little cost.
Has anyone tried it and if so what were the pro's and con's?
Or does anyone have any views or expert opioin on this?

[temi]

There are traffic and there are targeted traffic so its important to clarify the traffic you are getting, some site promise cheap traffic which they do deliver but its from people who are unlikely to be interested in you product. Most of the time targeted traffic from the demographic you want are usually not very cheap.