I have hunted both ways and have killed deer both ways. I would say that with the proper set up, they are equally effective. I do think it is exciting to be on the ground with the critters you are hunting and see them pop out in front of you at 10 yards, but I have limited experience, I have only taken about 3 or 4 deer from the ground with a bow.
It is really like mentioned earlier, you hunt how the terrian tells you to. If you need to be on the ground, do it. If you need to be in a tree, start climbing.
God Bless,
Nathan