In terms of difficulty, the game lets you carry about 12 gadgets that will each take down a minimum of one enemy - these gadgets refill up to full at every checkpoint where you will have had to face approximately between zero and five enemies (you can also kill enemies by shooting them or stabbing them for free).
There are multiple great multiplayer modes and some other online integrations woven throughout that have been completely disabled by Ubisoft after release - it COULD all work fine without their servers, but they didn't want it to, so the game no longer works as it should.