The gameplay and graphics, a mix of Assassin's Creed 3 and 4, hold up pretty well: the sea battles are as engaging as ever, making it fun to travel around the game's world looking for trouble to steal materials to upgrade your ship, and some land areas, especially New York, are quite attractive just to look at and explore, with tons of collectibles to find and zones to liberate. Nothing new, but still as enjoyable as before.
The most original and interesting aspect of the game is probably the story, which lets you experience things, for once, from the perspective of the Templars. Although it's shorter than usual and the missions are similar to what you are used to from previous games, being able to play as one of the 'bad guys' is quite refreshing.
More info: https://es.wikipedia.org/wiki/Assassin%27s_Creed:_Rogue