I see someone has mentioned Wong Kei's, in Chinatown. Dh and I actually got engaged there, and he had his stag do (a meal with friends and dbil) there too. They were fine, but a large party came in, and tried to move two tables together - so they could sit together - and got shouted at, and thrown out!
Another meal out, at a hotel where dh had been staying for a couple of days, and I'd come to join him for the last day - I decided not to have the tomato soup, because the huge, catering sized can of soup was on the hatch between the kitchen and dining room - and when another member of the party queried how freshly baked the baked potatoes were (having had one the day before, that had been minging) was told that they were cooked a couple of days ago and just reheated.
One of our favourite restaurants, when the boys were young, was Daquise, in South Kensington (close by the tube station) - it's a Polish restaurant, and when you walk in, it looks appalling - decorated in varying shades of dark brown, with plastic table cloths - but the food is wonderful, and the staff are amazing. When the boys were little, they'd take them off, and lift them up so they could look down the dumb-waiter shaft that led to the kitchen.
The first time we went there, on the way out, the elderly lady sitting by the door (clearly in charge of the place) stopped us to give us a cake in a bag, because the boys had been so nicely behaved.
Some people on here have mentioned over-salted food, and that's something I have experienced a number of times. I wonder if it is because, whilst in normal life, we have been trying (on health advice) to reduce the amount of salt we use, and food manufacturers have been reducing it too, this hasn't spread to restaurants, and chefs are still seasoning food to the extent that they always used to - and teaching new chefs to season that much too - and it is too salty for our palates, which are used to much less salt on a daily basis.
I watch programmes like Masterchef, and Masterchef Australia, and the judges are always going on about things being underseasoned, when it looks as if the contestants have seasoned it - and I always assume that it is a palate issue, and that the contestants' food probably tastes fine to normal people. Anyhow, I would rather add a bit extra seasoning to my food, if it isn't salty enough for my taste - that is a lot easier than taking salt out, once the chef has loaded it in!
Another not-so-good experience was in the Marco Pierre White Steakhouse, in Hotel Indigo, in Glasgow - the food was fine, but all the art work - every single piece - was huge, bigger than life-sized, black and white photos of Monsieur Pierre White, looking down at you from every wall. How up yourself do you have to be, to have your own photo as the ONLY art in your restaurant??