Depending on the model, you have to drill a few holes through the tile. Depending on the tile, that can be a pain. WIth the right drill bit, it's no big deal. A 'conventional' toilet anchors only to the toilet flange, so no additional holes are required. Some Totos use an adapter on the flange, then actually anchor to other brackets you install. In actuality, this produces a better solution, since now you've got the thing anchored to the floor better.
This Old House installed one in the last month or so...you can probably watch that on-line.