The quality of the travel experience on the tube highly depends on how old that specific line is.
The northern line, which is arguably one of the most useful lines for many people, is just not pleasant at all. The air is stale and full of soot particles, and you wait in a small cramped station perfect for claustrophobia. The trains are narrow and not air-conditioned. The central, victoria and piccadilly lines aren't much better.
The elizabeth or jubilee lines, newest of the bunch, offer comfort that is much more in line with the overground (wide and tall air-conditioned trains, large and well-ventilated stations).
Myself, I just avoid taking the tube and cycle instead. It's usually faster anyway.
This is about the overground though..
I've never really experienced it because I've always watched PAL which doesn't have that.
But I would have thought it would be perceived as flashing at 60 Hz with a darker image?