Alfonso's apartment is an excellent find and we are really happy we chose it for our stay in Oslo.
The apartment is located in Grünerløkka which is actually a much cooler place to explore than Oslo city imho with lots of cool restaurants and bars to visit. There is a supermarket within 1 minutes walk on the same street as the apartment for all the supplies you might need.
The apartment itself has everything you need to make your stay comfortable. It's very modern and most importantly clean! The 2 things that stood out for us was the wifi is really good and the water is perfectly clear and drinkable (always an area of uncertainty when travelling abroad).
The apartment is a loft so there are some stair involved once you enter the apartment building but it's not really an issue.
Alfonso was away at the time of our visit but he kept in touch through email and sms to make sure we had everything we needed. We would certainly recommend Alfonso and his Grünerløkka apartment to anyone and would return should we visit again.