We ate dinner there last week and had a good time overall. The cold board buffet has peel and eat shrimp with cocktail sauce, several types of cold salads, breads, and fresh fruit. Although you're asking about lunch, the dinner choices were not all that exotic. I had salmon which was really overcooked and awful. My husband had chicken with pasta which he really liked. And although my salmon was bad, the potatoes that came with it were really good and not weird at all.
Two of my kids had pizza which they loved and devoured. My oldest had the kids' pasta which he also liked.
Dessert is really, really good, and they brought us more because we liked the chocolate mousse cake so much.
As for princesses, at our dinner we had Aurora (who kissed my daughter on the cheek and thrilled her beyond belief), Jasmine (very funny and "sassy" as my kids called her), Belle in her blue dress, and Alice (a little strange speaking in rhyme with a pseudo British accent that sort of put DD off). Ariel was in the lobby greeting people and posting for pictures.
We liked it for what it was: a chance to meet princesses and to eat some basic food. The food was fine. I think you'll see that the food can be very Norweigian if you want, or it can be less so. I wouldn't worry about it being too "weird" at all. My husband's pasta with pesto and chicken certainly wouldn't be a common dish in Norway, and I don't expect the pizza my kids ate was very traditional either.
I'm glad we did it once. I'm not sure we'd do it again but that's just because I'll probably do a different princess thing on our next trip.