We also visited this venue on a Viking Cruise.
The building is spectacular and the views over the Duoro are to die for.
However, the catering for our 100+ people left a lot to be desired.
The soup was bland and the pork of the main course was dry (needed some apple sauce).
There was a long gap between soup and main when we could have had the Fado show, but instead we had to wait until after desert before we could see the show.
Nice to visit but don't bother with the dinner