Wife was in 50B. Good amount of space with no one climbing over her.
Didn’t get disturbed too much but was an overnight flight (Vancouver to Heathrow) , so footfall was minimal. Lots more movement in the morning before landing though since the bigger bathrooms are at the front. There is a curtain in front of the row 50 and a bit of space between the curtain and the toilets, so toilets are not a massive issue. Staircase was hardly used since it was cordoned off for the whole flight that I could see.
If it was not for the lack on windows in 50A and lack of overhead bins (had to use the ones over the middle row and the two passengers on that row were rude and not happy that I was putting my case in “their” overhead bins!!!!), would choose these seats.