I visited Primo Piatto at Disney's Riviera Resort prior to the great closedown of 2020. The burger that I tried (the Riviera Burger) is no longer on the menu for lunch or dinner at Primo Piatto, but I suspect the new burger that is on the menu (although slightly simpler, from a gastronomic standpoint) is just as good, and on the same quality level.
All in all, lunch at Primo Piatto was quite enjoyable. From a business standpoint, the location seems a little small for such a large resort. Technically, Primo Piatto is Riviera Resort's only counter service / quick service location. The setup, size, and scope reminds me a lot of the Gasparilla Island Grill over at Disney's Grand Floridian Resort.
Late-lunch (around 4pm) was quiet, and there were a moderate number of tables available. The environment is basically an upscale sandwich shop. There are a lot of hard, reflective surfaces around, so when full, I'm sure the location can get loud.
Service was above good and what we've come to expect from Disney Resort Dining … attentive and helpful, within the scope of each cast member's position.
Once things get back to normal, I'd be more than happy to revisit the location for another meal. For now (late 2020) most all Disney dining location menus are "reduced" (from a culinary standpoint, not from a monetary standpoint)… meaning, you'll find a lot of the same un-themed but still good burgers and sandwiches at multiple locations.