The most expensive city I've ever been to. One-hour city transport ticket (bus, tram, subway) - 4 EUR. Burger King meal - 20 EUR. Weather was horrible. However, the city is beautiful, and should be visited in July/August - April was just too early and too cold to enjoy. The Opera is a must-see, as well as Akershus Fortress overlooking the city and the Vigeland sculpture park. We made it 5 minutes too late for the Holmenkollen SkiJump Museum, so make sure you're there before 16:00.
Insider Tip:1. No money exchange offices at Ryge Airport, and nobody accepts EUR, only Norwegian Kroner. However, everything can be paid with credit cards. Many places/business refuse Electron cards.
2. Vietnam House Restaurant - great food, decent prices. Bernt Ankersgate 6B.