Bit far away from the city center, but within walking distance, if you are used to walking. Bus stop (Bus nro 30 to Bygdoy (citycentre) and back to the hostel (Nydalen)) really near, but the transportation in Norway is bit expensive. I stayed for two night and had the Oslo Pass for 24h, so half of the time was able to use busses.
Wifi was really good in the lobby, but bit slower in the rooms (2nd floor), so wouldn't trust it works in the upper floors.
Clean and silent rooms!