Sadly, we don't have one any more at our local school - just a pedestrian crossing, which I have seen children ignore and dash across instead of waiting for the green man.
I'd say a good lollipopper needs to be able to stand up to any rude drivers who resent waiting - something else I;ve seen, sadly. They also need to like kids! Sounds obvious, but I remember a very grumpy lollipop man we had when I was a child - thankfully not for long. I think he decided the job wasn't for him, but as a 6 year old, it was quite disconcerting to have your 'Goof morning Mr xxxx' answered with a grunt!