I was in the No. 1 lounge for the 2nd time last week and had a couple additional observations. Most of my trips are morning departures and I'm in the lounge from about 7:30 - 8:15. The library area is a nice place to sit and has not been very crowded either time while the tables and main areas can be quite packed.
The food/buffet layout isn't very good and causes traffic jams. There are 3 coffee machines and there always seemed to be a queue with people standing in the main walkway area. The coffee and tea mugs are to the left of the machines and it's difficult to get in to get a bowl of porridge and it would be nicer if the food was spread over a larger area and not right on the main pathway/corridor through the lounge. There is a coffee machine in the library area that nobody seems to use and was perfect for getting a refill. You can eat food in the library area - maybe people just aren't aware of that.
The real tragedy is the shortage of toilets. There are 3 gents toilets - each one is a nice individual room and are much nicer than what was available in the BA lounge toilets but I would hate to be there when the lounge is actually crowded. Don't wait to use the toilet on the way out of the lounge to your flight.
Another minor gripe is the check in desk process could be more efficient. When I would go to the BA lounge (mobile boarding pass, no checked bags) they would sometimes ask to see my passport and visa as I checked in to lounge. Now the first person can only check me in and give me a entry card to lounge, but I have to go to 2nd desk to get passport verified. Why can't they use both desks for check in to shorten the queues since the 2nd desk rarely has anyone there while the first desk is always backed up. They basically have 2 people checking in vs. 4 - 5 combined between the GC and GF lounges.