So this is a qualified yes.
I have 100% the same experience as you with the other games. I think our experience is common. The whole meta story with Juno is fucking offensively bad. The lack of intelligence with the general genetic memory concept is offensively bad. But when AC games are high camp, its lovely. That's what 2 + Brotherhood were - romps.
AC4 is a romp. It does the main stuff - action and running about, mission variety, upgrading - pretty much as well as 2 + Brotherhood. The setting hasn't been really fleshed out in a convincing way but its okay. The naval battles... are fun. Like, you just pick fights with fuckers and take what they own. Characters are fun. They don't rant. Templars and Assassins both are portrayed as rich white fools pontificating on the backs of slaves.. which is pretty refreshing.
Some things are bad. Brace yourself for meta-story stupidity that will now place the AC games in the universe of the AC games.. you'll see. Ubisoft also have NO idea how to run the companion app on iOS or the AC initiates website co-game stuff. The latter isn't even working yet. It's a mess. There's something called 'social treasure chests' that seem to be network-enabled - they don't explain how or why.
But AC4 is a romp. It is unqualified rompiness with a low bullshit factor. It lacks the artistry of 2, but it continues that fine tradition in a way that is unexpected. Don't come expecting complexity but its the best AC since Brotherhood, and if it had come straight after, the series would have not lost a beat.
I can say that having some idea of what your gaming taste is like after many years here, you will enjoy AC and feel it is worth it at full price. It is not unqualified. But it is a BLUE SKIES adventure with not-terrible story and fun characters.
Thank you, this is a wonderfully detailed post and shows a great depth of understanding both of myself and of the issues the series has had up until this point. Seriously, I cannot emphasize enough how this is an perfect, exemplary example of how the exchange of ideas on NeoGAF should strive to be.
Man, now I am really feeling confident I will not regret owning it when I get it on PS4. You are a good poster, bro.