If you'd like to visit Oslo and Espens place is in your budget you should book it.
Espen even told me and my girlfriend about the weather forecast and offered to help us making the sofa ready to sleep on.
Even though they got a dog, I did not have any allergic reaction. So don't be afraid of that.
Keep in mind, that the sun goes up quiet early in Oslo. So bring a sleep mask.
10/10 would book again.