So, what can we expect will be different about Assassin's Creed on the Wii U? Well, technically, nothing, as Ubisoft say that in terms of the series' graphics and engine, everything can come across to Nintendo's console just fine.
But the whole point of the Wii U, aside from the HD, is the fancy new controller, and there, Ubisoft can see some changes. Mostly as you'd expect: using the controller's screen just like everybody rushed to use the DS' second screen when that machine first came out.
Namely, things like a map and inventory control. A little more interesting is the idea that Assassin's Creed's database entries, which can be both educational and sometimes even funny, will expand and run on the controller screen while you're free to continue playing on the TV screen.
A little distracting, perhaps, but as someone who often skipped checking them out just so I didn't interrupt the game it, it's a good way to cram them down my throat.