I've done this fairly often (I wouldn't call it particularly hard, but I'm used to reading and walking at the same time, so I suppose that probably functions as practice,)

It's not super hard but it's harder than what most people do when they travel via a bus. I would guess that it's harder than what most LessWrong readers do when the travel via a bus. Realistically I don't think I will convince people on lesswrong to go dancing in a bus in public transport.

It's an exercise that trains physical stability. I myself could see the difference in my salsa dancing after doing it for a month. At the same time I find that the physical activity makes my mind more alert and I can put more cognitive resources the book better than I would by sitting down in the bus.