Depended on when you went and how busy the zoo was... sometimes it was, sometimes nobody there at all.. Historically all the Pandas at London(and in other zoos) have been hugely popular when they are young and more active and playful. As they get older they become less active and sleep a great deal- people still want to see them but are often disappointed by the rolled up ball of sleeping Panda and the visitor 'Pandamoneum' wanes..
The earlier 'Chi Chi' was a good example- playful and boisterous as a youngster her keepers would put on an entertaining 'show' session with her each afternoon for the delighted crowds. But as she grow older she became crabby and morose and even savaged a keeper while he was in the enclosure with her.
I am currently trying to check the exact timeline/course of events encompassing the ZSL Pandas 'Chia Chia' 'Ching ching' and the visiting male 'Bao Bao' from West Berlin who came temporarily on a short breeding loan around the early 1990's.
I should have added that if the adult Pandas breed, then the 'Pandamonium' starts all over again with the baby, but of course London have never succeeded with that aspect.