I spent 3 days in Prague and had an excellent 5 meals (I would highly recommend Les Moules), however I unfortunately went to El Centro on my last evening and it was very poor.
The staff were inattentive, they got our starter and main course orders wrong, and we were left waiting for ages without anyone coming to check on us. The sangria was watered down and the paella was distinctly average (I must confess I have had better ready made paellas from Sainsburys). Given the poor service and food the restaurant is extremely over priced.
We looked at some of the good reviews on here before going, and it was recommended by our DK guide book. I can only think that the restaurant must have changed hands since these reviews were written as it was nothing like we expected and ruined what was meant to be a lovely last night in Prague. Unfortunately it was terrible and I feel obliged to warn other travellers not to have their last (or first!) nights ruined at this awful restaurant.