However, being a fan of the show, I could not help but buy both games. I have not yet tested Unity so I would not compare (and I think in any case it is not comparable).
I find that Snape was ultimately done very well and not hurry to make sales. The game is mostly happening on the ship, like AC IV Black Flag.
What made the success of Black Flag is successful but brings the Rogue difference placing themselves in the camp of the Knights Templar.
We discover new places and I find that cities, particularly New York, are quite large and interesting for a game based on the navigation!
To mention a detail that is still important: money.
I find it relatively easy to be rich and can afford the weapon upgrades and boat, especially with the return of the bank which can collect the rents in his captain's cabin.
This is a good point for me because it's always boring to move in all directions to gather pennies while we prefer to continue the adventure!
The point that disappointed me regarding bugs. I feel they are a little more numerous than in previous versions, even if it is not (at least for me) unacceptable (even if the star is mostly less because of that) .
Overall I would recommend the game to those who are fan of the series and have gone through all the album and have not discarded their old console.
However, if some want to get into Assassin's Creed, I do not think this game is best for that. Although I appreciate it, it is far from the best and many characters from previous games return and can make understanding more difficult history.