AC4 is the best AC yet. That's not true of every AC game, but it is true of this one. The ending is a bit of misfortune (I completed all "contemporary" missions and objectives, and that doesn't wrap up satisfactorily, and neither does the main game, I reached the end of the main storyline having already completed every island objective, and was confronted with a map after the credits that shows the assassin/templar hunt missions (which rapidly evolved to my objectiveless map)).

The last chapter is named "saw that coming" and it's honestly more like "I didn't see that coming" in that there's no ending to speak of.

Everything in the game, EXCLUDING the ending, however, is amazing. They've generally cleaned up almost every aspect of the game but there are still a few missions that are frustratingly trial-and-error. The only significant reveal is John's identity, but they don't even play that one up as much as they should (he is a reincarnation of "Roberts").

The observatory is mildly more interesting than the libraries in AC Liberation, the contemporary story is generally stronger (except for leaving the wrapup with Rebecca et al to a text note in your log after you complete their extended hacking mission). Everything has been thrown into the fighting/ship combat gameplay, and at that, it excels. I wish there were more missions (Skyrim has a living world / unlimited quest system, there's no real particularly reason that they couldn't do the same with assassinations in AC at the very least). The ACL shipping missions are improved and expanded, and actually manage to tie into the game somewhat better (items you gain from the shipping missions include treasure maps and outfits/weapons). The hunting/crafting is pretty good, but the pirate's island construction is not nearly as good as the lengthy and satisfying (only satisfying part of AC3) homesteading side activity from AC3.

I'm still working to wrap up the fleet missions to see if there is anything interesting left there, but I've finished all but the final two rewards worth of abstergo challenges (I'm unlikely to 100% sync the game but I'm over 95%), so I think I can say that I've "finished" AC4, after 68 hours.

I guess it says something that I've put probably more hours into AC4 than into any other AC game, and I'm still left wanting more. Hopefully there's enough left in Edward's timeline (should be about 5 years or so before Haytham is conceived, cutting off his storyline unless he archived his memories like Altair did) to give us another game.

It's kind of weird that AC3 came out before this one did, honestly, because this is a better companion game to Liberation (characters from here work their way into that game's backstory but you had no way to know that before this game came out). However, since it has "completed" versions of the fleet mechanics from Liberation and the ship combat from AC3, it would be hard to imagine any way for this game to have been released before either of those two. Worth every penny of the $30 that I spent on it in an Amazon sale.