The whole "mother dies in fire in front of her son"-thing was very cliché, for example. And how he always kept fighting the good fight (even when it shouldn't have been apparent to him which fight was the good fight) and saying exactly the right things. I also think some aspects of his character sound interesting on paper but the execution is very lacking. For example, you could do a lot of interesting stuff with a naive protagonist who eventually becomes disillusioned by the world. The father-son relationship, too, although I think that was one of the few parts of the story that I actually found mildly interesting (I tend to attribute it to Haytham's involvement but Connor's inner turmoil might have played a part in it, too). One of the scenes that keeps popping up in my head when I think of Connor is the one where he talks with (I think it was Washington?) about slavery and Connor pretty much argues just the way a modern-day person would just to make him more appealing and likable to the audience. If they had really wanted to do something interesting with his supposed innocence and naivety, they would've let him suck it all up like a sponge, instead of making him wiser than a man who is not only much older than him but is also considered to be one of the greatest men of his time. That's a small example, sure, but it's one which really epitomises his awfully cheesy can-do-no-wrong attitude for me.
But yeah. some of the problems with Connor's character probably have to do with the story's presentation. It just felt like a disjointed mess which had way too many historical events crammed into it just for the sake of it and without any care for pacing or dramaturgy. Most of the characters didn't get any proper characterisation. Achilles is probably the best example in that regard. He was supposed to be an important part of Connor's life and played a very significant role in the story but we never really got to know him and then I think he died and the game presented it in a way that told me I should feel bad because this very important character had died but I just didn't because the game had never really given me a reason to care about him. But this goes for most characters, really. That weird guy who ended up being the main antagonist (I've forgotten his name), for example. Couldn't have cared less about him. I think the only characters I really ended up finding interesting were Haytham and Connor's mom. So yeah, if he had been presented in a different way, maybe I would've found him more interesting (although I would definitely have still rolled my eyes at some of his actions and statements). But as it stands I just don't.
. See my edit.