my comments...
- the couch looks like it's made of plastacene... need some form of texture there. No fabric is completely featureless. Also the specular is a bit broad for fabric. check out the ikea website, they have couches very similar to this.
- the chair model is good, but the lighting is a little odd, I'd move it a bit to eliminate that dark shadow behind the back support. Also, wood like that generally is a little bit more glossy.
- the floor is matt as well. Makes it look like woodprint carpet. Use the actual texture in the specular channel... (depending on your software) you may need to use photoshop to darken, or lighten it to get the right amount of specular, but that will add quite a bit. Also there should be SOME reflection of the objects in the floor. One can actually see reflection on concrete at some angles. a reflection free surface is very rare, and when you see one it's usually completely matt, like carpet or rough fabric.
- perhaps add a second chair? agains the wall or move the scene around a bit... the chair sitting like that in the middle of the floor feels a bit staged and odd. People don't generally orphan a nice chair like that in the middle of the room.. all by itself.

For that matter, add a coffee table or a side table with a lamp. This will go a long way to selling this as a real space.
just my 2c