Positive: On my way to work, there was a rather loud and fast sports car revving alongside me for a while. I essentially went faster than it, what with all the traffic. I could totally hear the driver's penis crying out in frustration at revving, going 50MPH for about 30 feet, then having to stop, thanks to the fact that San Francisco is crowded and the bike lanes move fast.
Negative: On the way home, I almost got hit by a car, at a rather tricky spot. Basically, Division keeps going straight, but the right-side turn onto 9th splits off a bit early, and a lot of people assume they can just speed on through it even though the bike lane crosses the split part (which is a bit hard to see because of the complex bridge stuff, and it's only marked as a bike lane in some places). I always look behind me to make sure there's nobody about to hit me, which was also the case this time, but some person was driving really fast (I'd estimate nearly 40MPH) on Division and had to stop suddenly. They didn't hit me, but they did honk at me, as if it's my fault they didn't notice me safely moving forward while they were being too stupid to yield to me in the bike lane.
Oh, and further along Division, a bunch of people thought it was okay to pull pretty far to the right, crossing over the semi-marked bike lane. That's one of the aggravating things about a lot of the bike lanes in San Francisco, where they're not marked off but instead have occasional bicycle symbols in the space where the lane would be marked. A lot of people don't realize that it's a bike lane and seem to just plain ignore it.
Oh, and on that note, this morning I almost got hit because some idiot was waiting for a gate on Division to open and was basically blocking the entire right lane (when they could have pulled forward by at least 5 feet) and bike lane and I had to swerve around, and the big ol' SUV which was also in the right lane figured it could just keep going at its same speed and not slow down even though, you know, cyclist. A lot of people here seem to completely ignore the signs everywhere which state quite plainly that bicycles are traffic and have the same right-of-way rights as cars.
Basically what I'm saying is Division is kind of an unsafe street and it needs better bike lane markings.