One thing I like about Karl Johans Gate is that there is always something happening. Here someone drawing your portrait, there a musician and over there a living statue. Some are good, others aren't and you may like or dislike these people. I used to dislike it (as I felt I was begged for money all the time when walking this street) but my mindset has changed a bit and now, I am always curious to know who will be there and what he will do.
Last photo I took was of an original living statue
The person was not particularly skilled for the "job" (was moving too much I believe) but the costume was original and nicely made. Looked real at distance. I wrote more about it here.
Today, there was a "spray painter", you know the kind who use aerosol and so on to create stunning images. I am always curious to see what the result will be.
Anyway, if you intend to spend some time in Oslo, I think that Karl Joahns gate is worth a visit. I cannot promise you there will be something interesting but you never know what will happen there!