I'm several hours in to Rogue and I have to admit, it is not nearly as impressive as AC:4.
The story doesn't capture me in any way. I still don't really comprehend who my character is or what he's all about. This part was laid out very clearly in AC4.
The setting seems weird to me. There are enemy soldiers scattered all around whom I can kill.... but I don't know why I would want to kill them and they themselves don't seem to care that I exist.
The ship handling is off. It doesn't feel so much like I am managing a ship of sea, it feels more like I am managing an arcade version of a ship at sea. The handling is, to be blunt, too tight. Movement on sea is actually too easy and fast.
The character seems to not respond quite as sharply as the guy in AC4 did. It's not a terrible game-breaking deficit, but it is just a little on the sloppy side.
Level design is also not nearly as clever as AC4. I know the AC games are somewhat on rails in the sense that "That tree leads to that ledge which leads to that prize", but in Rogue the whole thing seems so much more obvious and monodirectional.
Overall I am enjoying Rogue because it is essentially just AC4 again, which is fine. I sort of wanted to play more AC4, and Rogue fits that bill. That being said, it is not nearly as 'magical' (if I may use the word) as AC4 was. I will almost certainly play through Rogue and enjoy it and think it worth my while... but it is no AC4.