My principle issue with Kenway is that he has very little agency. He just rolls what whatever's going on, hoping to get some dubloons out of it at the end.
AC4's strength lies very definitely in its gameplay and setting. The only characters I've found particularly interesting are that merchant, and the Templar group. Evenwasn't all that memorable beyond being the main Assassins contact.Spoiler:Kidd, who by rights I should be all over given I have a thing for crossdressing women,
The only thing he cares about is making money, which makes him the best protagonist since Ezio. He's perfectly suited for the game itself, which (aside from the plot) is really just about killing people and animals to become more powerful. It's refreshing for the game to acknowledge what it really is through it's characters, as opposed to Far Cry 3 which wrapped a whole bunch of terrible bullshit around it's vapid and repellent core. I have a serious problem with killing animals in video games, but at least in AC4 it makes a little bit of sense within the historical context. Not sure why you need whale skin to make holsters, though.
I'm not going to explain it very well, but I think one of the main reasons people don't like Connor as much is because his obsession has no ties to what he is actually doing. Altair was all about the Assassins. Kinda self-explanatory. Ezio wanted revenge for his family, which was murdered in a Templar plot, so it was natural to oppose them, especially considering his lineage. I haven't played 4, but Edward wants to get paid, from what I understand, and uses the Assassins vs Templars as a means to that end. Connor, on the other hand, talks about family revenge like Ezio, but the attack really had nothing to do with the assassins, and frankly both Assassins and Templars fuck his people over, so it seems like at some point he's an Assassin because the game is called Assassin's Creed, not because of anything to do with Connor himself.
I am finding it hard not to play this game as a super-fancy HD version of Sid Meier's Pirates, only with the ballroom dancing replaced by stabbing every single guard in every single slave plantation just on principle.