I haven't actually played any of the 4 ACs that have been released, not sure why. They always had an appeal but probably just one of those games that didn't quite make the cut when I had to buy them for some other game. I like that Ubisoft has said that they are designing III to be a good jumping on point for people who haven't played it but are going to also do their best to keep the wide appeal of previous games for people who have.
I more I read and watch about this title the more I think it will be the one where I jump on board. The story line in this one really has me intrigued.