i can forgive a lot if I end the game in a satisfied state, for whatever faults the Assassins Creed games have, every single I ended with "well, that was a decent enough story". Same with stuff like the Yakuza games or others everyone may not like. I was satisfied with FC4, FC Primal, and FC5 even though it was quite a slog to get to the ending.
The ending of FC6 is bad and extremely unsatisfying. It really made me wish I hadn't played the game. So if story matters to you, then skip FC6. And thats ultimately the problem, the ONLY thing FC6 has going for it is story since game mechanics and combat is an utter joke. You can cheese and headshot everything, the only time the game is a challenge is when its all fucked up and shit doesn't work. Its pretty I guess and kinda cool wandering around fake Cuba, but there are so many fuckstick annoying characters who constantly remind you that America sucks, communism rules, being trans and gay is super important, and white people are evil. I can put up with that bullshit in a good game but fuck off in a shitty game.
If you played Mafia 3 its a bit reminiscent of that, in that there is a decent main character and a few side characters but the game gets clogged in a middle section that never seems to end just doing the same shit over and over before you can get to an ending that isn't that great. Mafia 3 was way, way better though.