I hate them.
At least in the area I'm in (the Inner Sunset), they often cruise around with no passengers while waiting for a request. While doing so, they circle around idling at 10-15mph, pausing for 30 seconds or more at stop signs. It's long enough where just when you decide they've completely stopped and start to go around, they "wake up" and start moving again. I have personally been held up by four separate Cruise vehicles acting this way within a ten block section of a single trip. It is maddening, and there's no safe or reasonable way to pass them. I am generally quite patient and not particularly affected by road rage, but I'll confess that I have spent significant amounts of time fantasizing about an Office Space printer scene styled destruction of these vehicles.
They need to either find places to pull over (ideal) or drive like normal participants in traffic. Their current behavior feels disruptively slow (cars end up backed up behind them) and simultaneously unpredictable and confusing.
Worse, in other areas like Fell St., they drive exclusively in the left hand lane while driving 15mph below the flow of traffic. This actually causes significantly extra traffic during busier times as that street is often at or near capacity. It also disrupts the design of that road, which has a "green wave" of lights paced at about 30mph. Dramatically fewer cars make it through any section of road when you have one car driving 20mph that prompts everyone behind it to merge over to the right, further impacting the throughput of other lanes.
I've also seen acute instances where they completely fail in situations where humans would cooperate to solve an issue. In one instance, a left-turning Muni bus was unable to complete the turn due to a Cruise vehicle coming from that direction. The Cruise vehicle had entered too far into the intersection before stopping. There's paint on the intersection to indicate that cars need to stop further back, and the Cruise had failed to obey this. The bus was unable to back up due to traffic behind it as well as visibility concerns, and the only real solution was for the Cruise vehicle to move out of the way. There was, however, no way to instruct, plead with, or otherwise convince the Cruise to move. It had no place in particular to be, so it had no reason to decide to do anything other than sit in place with infinite patience and wait for everyone else to resolve the situation on its behalf. I watched as this completely gridlocked a busy intersection for at least five cycles of traffic lights before I got bored and left. I have no idea how they finally unwedged the situation, but I have to imagine it involved the bus driver getting out and having the cars behind clear a space for it to back up and allow the Cruise to complete its prime directive and pass.
Will these things get better? Sure. But right now, they are inexcusably bad drivers.