I also think AC3 is a great game, and so do other people too, all it took was for them to reskin Connor, change the environment, barely add any new animations, and streamline the hell out of boat combat to make people think that AC3 was a good game. AC4 is a great game, but it wouldn't exist without such a stable template like AC3.
Don't forget the more lively towns and not just responding Connor, but actually putting a likeable character in his place, that helped.
Anyway, game is growing on me. Last parts of act 2 have had the story pick up a bit. It's an OK story now, but not horrible like it was. Also stopped driving and taking the train everywhere to get away from the stiffness, shoved the sensitivity down for aiming and using a silenced pistol almost exclusively.
I still feel other games are better, but it's moving away from average territory for me now.
Also, performance wise, if it wasn't for the vram demands on anything above medium textures, I think it would be good. I'm mostly around high and ultra for most settings with ambient occlusion off and temporal AA on with a 560ti.
Almost stopped playing after an eavesdrop mission though... Goddammit Ubisoft.