IMHO, Akershus is perfect for lunch. I love the cold buffet, bread, and soup. I have not been since they implemented the new system, but I am anxious to try it out. Previously when eating there I've stuffed myself on the cold items and soup. I am particularly fond of the cheeses, shrimp salad, and smoked fish. I'll have to force myself to save room for the lamb and cabbage--sounds fantastic!!!
If you go, definitely try to go for lunch due to the lower price. I also find the cold items more appealing at lunch time. If you enjoy beer, you must have a Ringnes. It's one of my favorite beers and I wish I could find it locally.