I've been to Sweden roughly every other year for almost a decade. Stockholm, Malmo and Goteborg are great, but a little lacking in "grit" if that's what you look for in a city. After a couple of weeks it can get a bit boring if you are used to chaos. In many ways, vibrant food and entrepreneur culture is still emerging compared to the rest of the world.
Pretty much the whole of Sweden (except for suburbs) is great if you like quiet, beautiful living. I would qualify that by saying that outside of the sthlm area, suburbs can have woods and streams and cool shit like that.
Christmas is particularly difficult as there are days with no sun, and it can get depressing (my friend's neighbor hung himself on his balcony). But summer is so beautiful. Everyone is out, picnics, parties, etc. There are also loads of places to go in the countryside, and borderskipping is easy. You can take a bus to Denmark, there are cheap flights to Spain and everywhere else..
I'd visit before moving there just to see if it's your thing. The cost of living is particularly high compared to say the PIGS, but like people mentioned, health care and education are what you get in exchange.
It's also pretty safe. I left a bag with a few thousand $ in a cafe and didn't realize til some hours later. When I got back, my bag was still in the same place despite the restaurant being super busy. I've also walked home from clubs/ parties at 2-4 am and not had any sort of trouble except for once, to a manageable level.
Personally, I could stay for probably 5 months tops, and would need a bit of a change in scenery or a place with more of an element if surprise and uncertainty... But that's just me, as I grew up in a place with total chaos and much less reserved people.
