Fantastic first piece
As a first-go in 3D modelling, this is some excellent work with a lot of attention to details. I really liked, for example, that you beveled almost every object, that there's a lot of depth-of-field blur, and that all the shadows are realistically soft.
Each object is very simple, which speaks of an efficiency on your part. What I mean is, I might have added more polygons on the couch and then did a random-displacement of the vertexes, so that it seems more like a cushion and less like a plastic mold. All the textures are only one or two layers deep, which makes the paint cans look a little unrealistic, and as you said everything looks a little too clean.
I DON'T consider this negative criticism, however! Given that you only had 4 weeks, you managed to give each object about the same level of detail and quality. It looks broadly consistent, if a bit amateur. The consistency between objects, in fact, gives the render a video-game feel instead of an I'm-just-a-beginner feel. It seems to me that you maxed out your potential and delivered just as good an image as you were capable of given the time limit. And that, sir, earns you an extra point.
I hope you do more 3D in the future. And after a few more years' experience, this would be a great model to go back to and spruce up. As it stands, it is a piece for a beginner to be proud of.