The constant loading...
when you're on horseback is annoying.
The fact that I've got to rotate on the spot (something I normally only expect from PC games) when I enter an area to make sure everything's loaded is also annoying.
That being said, I'm having an absolute blast with the game. It's good fun. It continues ACII's plot (and that, more than anything, is why I'm playing the game), even if it did do the whole "remove all the weapons" thing way too early.
Until City Of Heroes releases Issue 19, this is what I'll be playing.