I didn't have that experience at all. In previous games, I would hire courtesans and walk in the middle of the 4 of them so that I was hidden and I'd regularly pop out of the area you had to walk in for no apparent reason, which would blow my cover and I'd be detected. That didn't happen once in this game.I also thought that the AI for the hired Romani/courtesans was worse than the last game as well. They could barely keep up with me when I fast-walked.
The one thing that did get on my nerves a little is when you have to walk next to a character on your way to a mission. If you got close enough you could let go of the controls and you'd automatically walk next to them and the camera angle would change, except what would inevitably happen is that Ezio would almost immediately hit some object in the environment and pop out of that "auto-walk" mode.
On an unrelated note, did anyone notice that there's a particular sword that you can get that when you unsheath it, sometimes the guards will see it and get scared and run off? I thought that was a pretty cool touch, like they're thinking "shit, he's got the blahblah sword, leg it!".