We enjoyed the Viking River of Gold trip but would rate this a 3.8-4.0 versus other European river cruises. Sightseeing in Lisbon and Porto was pleasant and interesting but not at the level of other major capitals. The Douro River valley was delightful, scenic and quiet but devoid of sightseeing. Side trips to small towns and historic sites required lengthy bus time. Highly recommend the add-on trip to Santiago de Compostela for its historic significance and architectural beauty. Also enjoyed the visit to Salamanca. Note that Viking hotel stays were excellent. Staff and guides were top notch. As for the dining room, food and service was certainly good but not great (if you want fabulous dining take Tauck). In general I would recommend taking all the other river cruises first (Danube, Rhine, Rhone) which have superior sightseeing itineraries and save the Douro for last if you enjoy the river cruise experience.