A triumph and a highlight of the year indeed.
Positive aspects of the game:
-Wonderful world / map
-A lot of things to do
-Stealth works very well, you can chose how to approach your taget, etc..
-Cities are better than AC3 (for free running)
-This is A TRUE AC GAME, and the most accomplished of the franchise.
-Combats are slower than AC3...
-...There are less weapons, less new types of ennemies...
-... But naval battles are amazing !
-You'll play as Edward like 10 minutes after launching the game on your console
-Naval is amazing
-Economic system of AC4 is easier to understand and really well made (you board ships, and sell ressources)
-You'll need to upgrade your ship to succes on seas. To upgrade your ship you'll need ressources. You can get them by boarding ships.
-Taking forts have an impact on Edward's progression. It will reveal the location of special places such as caves.
-In all main or secondary missions you can play stealthy if you chose to.
-The involvement of Edward in the Templar-Assassin conflict is a bit predictable but still well done
TO CONCLUDE: AC4 is the most successful game of the franchise. Better mechanics of gameplay, better level design, the game is a real success.
You'll need about 20 hours to complete the main path and 50 hours to complete everything.