I have played it. And it was amazing. You remember the first time you played Assassin's Creed, or Assassin's Creed 2? It's like that. It plays differently enough that it's like a brand new game, not just the next one in the franchise. That's my opinion anyway. I highly recommend it. And buy me a copy too, I had to give my sister in law's boyfriend's copy back.
I have played AC3 and I can only recommend it! It's awesome! Great story, amazing characters, beautiful level design. Although they still haven't fixed most of the bugs from Revelations and Brotherhood. -.- Meh, whatever. It's still an an dignified ending for the series.