The only experience I have is with the EKTORP range. I had the two seater version in white (I know, bad choice of colour). But the colour aside, I found it to be very uncomfortable. Very hard indeed. We actually ended up replacing the foam in the cushions to make it more comfortable once the original foam just lost all firmness and shape. When the covers are washed (as per instructions) they distort making refitting them a nightmare and also they then never look as good. The covers are also cheaply made. They break particularly where the zips are sewn...the zips are also not that heavy weight to cope with the stresses on them. The cover also un-stitches itself in various places.
I would stay well clear as even though they're very affordable, in this case it was "you get what you pay for". But like I said, I can only speak for the EKTORP range. Which admittedly is a budget range.
Our DFS sofa, which was similar size and style (but not white!) but a fair amount more to purchase, 7 years on is still in great shape and has suffered none of the problems we had with the Ikea one which was bought at the same time and gotten rid off 1.5 years later.
