Seeing further is only one advantage, you also get your scent up off the ground, a deer can walk right under your stink as it blows away over its head. Climbing stands are also very mobile, you can move around and once you're setup there is very little evidence that you were there an hour earlier. Finally, deer don't have natural predators in the trees so only the smart, experianced ones look up, a ground blind is something new and out of place that deer will notice and avoid, if your in a tree stand theres a good chance that they won't even notice the change of scenary(sp?) if you haven't trimmed to much or left too much scent on your way in.
I love ground blinds, especially for turkey, but a deer will notice a new one in a second, take the time to build natural ground blinds and hunt from them next year, after the deer have accepted them, but don't expect to construck something during season and have the deer not notice it (turkeys are a different story).