Trying to move around cover or climb walls. It's got a bit of the Assassin's Creed syndrome, where it can be a bit off. I try to get off cover, and it might not let me fast enough. I tried to climb a wall and walk along the top, and it immediately had me jump off the other side, making me run all the way back around to get on top of the wall. It's nothing major, just a bit of an annoyance.
The handbrake seems rather useless while driving, though. Using it to turn's not really any different than using nothing or tapping the left trigger.
Hah, I didn't know that was an A.I. thing, the first hack. I just assumed someone was trying to annoy me. I've been hacked once after that. What was weird is that it never had a progress meter. I thought the guy hadn't found me to start hacking, but when I finished, it said he was at 74% or something. Either way, I took him down pretty easily. I just got behind a wall, hacked a camera, and looked for him.