Getting hold of Norwegian craft beer in a pub context can be quite difficult in Oslo, and the city's only brewpub doesn't stock the bottled stuff from the other microbreweries. It does, however, produce a rather good range of homemade beers and at prices which are excellent for decent Norwegian beer accompanied by a table to drink it at.
The stout is particularly recommended, as is Amber X, their American-style pale ale.
The bar room is quite small, with a combination of booths, high tables and standard café furniture with the bar in the middle and the brewery in the corner. I can imagine it getting quite crowded at peak times.
You don't come to Oslo to sit in the pub drinking beer, but it's still great that places like this make it possible.