Norway usually win or end high up in the rankings when it comes to lifequality, happiness and these kinds of things.
I think this much has to do with the safety people here have concerning welfare and economy, and the right balance between work and sparetime. If someone needs help they get it. People also have the time to balance between work, family and other sparetime. You have good time to spend with your kids, and you also have time for your own activities, be it training indoor, hiking in the nature, facebooking or visiting a cafè for example. All this gives us the energy to feel good compared to places where you have to work much more.
If you have the time in other countries you often don’t have work and don’t feel the economical safety. There’s no doubt that Norway has been very lucky the last years compared to for example Spain when it comes to these things. The middle class in Norway is very strong (most of the people in Norway is middle class), and that is one of our advantages.
The nature is very important for a big part of people in Norway. We like to use it whatever way we can, according to our interests. This is where many norwegians after a busy everyday (of course we have busy everydays like everybody else) go to 'charge up'.
Of course, we have colder weather than most other countries. So to live here you have a big advantage if you like nature and all sorts of weather. If you mostly like big cities and warm weather you shouldn’t really concider Norway in the first place. Norway of course has some problems like all other places in the world, but they're fewer than other places.
Remember that even if 6 months of the year is darker, also 6 months of the year is lighter than countries south of us!