Rogue is a very divisive Assassin's Creed game. It's technically a standalone expansion or direct spinoff to Black Flag, which isn't a bad thing in my opinion. This means that a lot more focus is on the story. But even then, the story is too short and underdeveloped for its own good.
Trust me, I love this game's story and protagonist. But I can't help but feel like there's a lot to be desired. Assassin's Creed stories have always had a somewhat memorable cast of characters with some sort of depth to them. Whether through dialogue or just overall characterization. Rogue's supporting cast is weak, both assassin's and especially Templars. The cast isn't that memorable and don't really leave that much of a lasting impression. And while some of the dialogue is fairly good, it only goes so far to develop the characters. Some narrative moments also don't feel fully fleshed out or told in the best way. The modern day storyline should've completely been scrapped from this game in order for the main story to properly flourish. Rogue's modern day really doesn't do anything for the game's overall story, except waste time and connect it to previous games a bit more.
But what's great about Rogue's story? The protagonist (Shay), the connections to Black Flag (as well as Liberation & Assassin's Creed III), the setpieces, the drama, and a few certain character/story moments. But Rogue's story is too rushed and underdeveloped to truly be great. Wasted potential, really.
As for gameplay and presentation, Rogue reuses the framework of Black Flag. Same engine, same assets, same gameplay. Which isn't bad, since Black Flag's framework was already so great. Rogue expands on the framework in certain ways, though. Naval gameplay is a lot more convenient and interesting. The addition of stalkers adds a sense of suspense and fear to the exploration. Everything else, like the on-foot combat and stealth, is fairly the same as Black Flag.
But even though the game uses the same assets and framework of Black Flag, the art direction and atmosphere is different here. Black Flag was vibrant and adventurous. Rogue is cold and immersive. Color schemes are less saturated than Black Flag. The atmosphere is more isolated and somewhat muted. The soundtrack still carries that epic personality of the Kenway Saga, but there's a slightly more meditative and darker edge to it.
Assassin's Creed: Rogue is really carried by its reuse and slight expansion of Black Flag's framework. The gameplay is solid, and the art direction and atmosphere is appropriate and immersive. But the story, which is the biggest selling point and most notable difference this game has to Black Flag, lacks the polish and development that could've made it the most unique Assassin's Creed tale.