Frilly -- I would say that it kind of "depends." A 6-foot fence is easily jumped by a deer, but if the space inside seems too confined, they aren't likely to do so. So, it kind of depends on how large an area you are fencing, and what else is inside the fence.
I have a 2-1/2-foot fence around my garden, in the middle of the woods here where we have lots of deer, but no problems with them getting into the garden -- which I attribute to the fact that I have several tall trellises for beans, and large wooden tomato cages and a greenhouse on one side... I think they just find it too intimidating in terms of possibly getting trapped.
