Is the Deluxe version worth it?
I have to say No. Quite a lot of stuff is for MP anyway. Personally, I haven't started that even once. And those items you get in the Deluxe are not even really better than the gear you get regularly.
I thought the story came around and delivered at the end, except the execution in terms of the story build up was really poor, especially handling all the characters like Blackbeard, Mary, etc. I found the story incredibly underwhelming up until things start snowballing after Blackbeard dies (no that is not a spoiler, open up a history book). All in all, I came away with a pretty decent impression on this game, though for some reason I found AC3 more compelling and fun.
Funny fact: AC3 was the only one I actually played through before AC4. The parts before bored me too early for me to pull through to the end.
Overall I really enjoyed the game which is mostly due to the awesome pirating part in it. Though I'd consider the story solid. I like the approach of Kenway not being Templar nor Assassin right from the start. The selfish part was entertaining, I think.
Good game which might have been even better w/o it even being connected to AC but a standalone title by itself. Worst part was this useless nonsense outside the Animus. That was actually really, really bad. Luckily just a very small part of the overall game.
25% off on steam for those who haven't checked
Here it's just 25€. That's another 12€ less than the German pricing Steam sale but it's a UPlay key.