I can't vouch for the long term durability as we've only had it two weeks, but we have the 3-seater stockesund which looks quite traditional rather than ultra modern. It seemed very well constructed when I was putting it together and it is certainly very comfortable. I really like the fact that the covers are machine washable and you can but another set for about £150.
We've had the kivik for a year and a half and it's still in really good nick. For the price its definately worth it, I don't expect it to last a lifetime but we will get a good few years out of it still.
We have a 2 seater ektorp in the family room that's so far withstood 2 years of abuse (lego/starwars battles, , turning into dens, lying/sitting on anywhere but the seats etc) It's not the same as my multiyork sofa in the living room but as it was a fraction of the price and was easy to buy a spare set of covers for without remortgaging our house it's a bloody good deal.