Café Mario is the restaurant at Nintendo of America where employees eat. Due to the confidentiality of Nintendo of America's headquarters and that no one is allowed to take pictures inside the building past the front desk, not much is known about the restaurant.
Since lots of companies have built-in restaurants, Café Mario might not be that special. Apparently it seats up to 600 people. In July 2018, food poisoning was traced to the restaurant.
Based on the limited information we have about the restaurant, we can assume the food is good.