My wife and I stayed on a tour for three excellent nights, I designed buildings for 45 plus years and the Sheraton Porto design is up there at the top, quietly stunning.
Despite its modern appearance it was very comfortable and quiet also all the staff were a credit to Sheraton.
The food both at breakfast and at evening meals was not only plentiful but was varied and tasty.
The only slight downside was how far out of the centre of Porto but this can be overcome by public transport or reasonably priced taxis.
All in all a very pleasant stay and certainly 6 star value.