Depends on what kind of hunting you are talking about. Bow hunting I've had much more success out of a tree stand, although I have taken a couple deer shooting out of a ground blind.

However, I prefer a ground blind later in the season when hunting with a muzzleloader. Sure, the deer sometimes notice that it's there, but they don't pay much attention to it from 100 yards out - that's the range I usually take them down.