Mostly it's irritating to be driving in flat light but it can be also dangerous. When light is flat it's just impossible to see any surface definitions. Everything is just white and you can't see if there is some slopes or you can't even see the surface of snow.
When we were on Dunérbukta conditions became just like that. Visibility was actually pretty reasonable but light became totally flat. We were driving really carefully on the moraine, between the stones which were sticking out of snow and giving us a meaning to surrounding. Suddenly a scooter front of us stopped. The driver got out of his scooter and looked little bit confused. "He just disappeared", said him, meaning the scooter front of him. We left our scooters and started to walk on the scooter track. It really looked like the track disappeared in nowhere.
First I saw a sledge, somewhere far down, then a scooter little bit apart from the sledge and a man beside it. They had just fallen right down some meters. Luckily the man had got rid of the scooter to avoid landing on it, because that could have given him serious injuries. Instead he landed on quite soft snow and just got short of breath but didn't get any broken ribs, split spleen or whatever. Ironically enough he was hurting mostly on the breast because he had a satellite telephone on a pocket and he landed on it.
Now I knew there were a vertical drop front of me, but I still couldn't see it. I saw the place where the scooter track ended up, I saw our friend with his scooter and the sledge far down, but I still couldn't see the drop. That's kind of spooky.
But the most important thing was that our friend was uninjured!