Not a complete overhaul. Recently I've seen people calling the Revisted saga "what the special editions should have been", which I think is an excellent way to describe them: keeping the colors intact (even corrected), the lightsaber blades beautifully corrected, fixing the most unnoticeable errors, and having a surprise here and there. Ady has an entire unit filming new footage for the Battle of Hoth, for example, with props built, as far as I know, from scratch. He was even making a Wampa, though I don't know if that ended up working or not.