Sofa looks much better scaled now. Still need work on the sofa/chair sides to reduce the stretching and I'm really intrigued as to what that strange little seat come tea table is in the middle
It's kind of cool, like a place to chain the kids while they watch sponge bob
As to rounding off you can do it two ways. 1) by using more polygons in the model to create curved faces along with smoothing groups. Or in your texture by the use of blending black and white shading to create a curved look to the eye. You can also use the same method to make it look like the sofa has 3 cushions instead of one whole one.
Textures can really make a low poly model look higher poly than it is
p.s. If your modelling app has it, turn on the apply checkerboard pattern while building your UV Map. If not use this texture (attached) as your material.
It's an excellent way to spot stretching and deformities etc.