I haven't been to many but the ones I have tried I'm always left confused on how they have so many locations. It's always expensive, the menu options are pretty basic, the more interesting dishes are small portions or skimping on the good ingredients despite having the premium price. I wouldn't go there for a special occasion as it never feels special but I'd also never go for a quick meal because it's so much money for some pretty simple food.
The ones I've tried are Pizza Express, las iguanas, Wagamamas, and probably a couple more that have just escaped my memory out of them being so forgettable.
What ones are worth going to?