But, if the game works because of the free-running parts, why add a tower defense minigame where Ezio Auditore gets to stand still and play general as Templars try to take assassins' lairs around Istanbul? Ezio may have to order people about in his running of the assassins' guild (one of the tweaks made to Brotherhood that is again present here), but that is really just sending people on missions, not having to watch as they complete them. This new tower defense minigame stands Ezio on a rooftop where he then has to place commanders, archers, riflemen, etc., in order to block the advance of Templar troops. Ezio is allowed to fire his gun, but it is forced to be stationary in a game that works because the character moves so beautifully.
One of the other, alleged, main tweaks to this game is Ezio's trading in his normal assassins' blades for a hook blade which mostly just allows him to catch onto the sides of buildings without falling. While that might be a great sort of addition had Ezio not been able to do the exact same thing in the last two titles without the hook blade, he has been able to catch himself and the jumps he can make now don't seem better for the addition of the hook. There are moments using the hook where you'll wonder if Ezio simply needs the crutch because he's gotten a little long in the tooth.
Revelations also sports a different controller scheme. It functions far less well and will be greatly confusing to those who have traveled with Ezio before.
There are also bombs added to this game, which isn't a bad twist, and the Templars not the Borgias play the main baddies. But, those are not exactly reasons to go out and spend $60.
The reason to go out and get this game is if you love the last two titles enough to want to see what happens to Ezio next. There really is a lot of this game that's good, but none of what makes this game good isn't in the earlier titles.
Revelations does take you out of Ezio's life at points to throw you into that of Altair (from the original game) or Desmond (the poor modern day schlub around whom the game is framed). While the Altair bits are enjoyable, the Desmond ones only serve to remind the player that we are really Desmond the whole time, and that Desmond is just living through Ezio and Altair's memories. Honestly, that isn't the sort of thing the game should emphasize because then it has to repeatedly point out it's DNA-memory-relive-past-lives-in-a-machine-called-the-animus-to-find-artificats-spread-throughout-time-in-order-to-control-the-present-day-world story. The tales of Ezio and Altair's lives are great and are more than enough without the Desmond frame which has never been compelling. Playing as Desmond one has to wonder if at some point even the creators of the game have wondered why they saddled themselves with such a tale and didn't simply set the whole thing in the past (much of the Desmond story being optional this go round may indicate they do).