I think you need to work on the materials. Do they have 100% roughness?
If so they shouldn't as a general rule. Put some bump or displacement on them. Everything is too flat and clean. Don't be scared of a bit of dirt or uneven surfaces, as this is what you will be seeing in reality.
Look at materials in the MXM Gallery to get ideas. Use materials from the MXM gallery.
I find that getting a good result is rarely possible without good materials.
Also Even the tiniest of chamfers on edges make all the difference.
Nappy,
There is something about your materials that doesn't sit right. it seems to me that your materials are making your image look very flat. have you looked at Mverta's material videos? they are very helpful. http://think.maxwellrender.com/masterin ... _3_77.html
the lighting looks much better.
the distortion of the vertical lines disturbs me a little.
try looking horizontally with the camera and adjust the position with a negativ "y offset" like with a shift/tilt lens
Nappy, the main material that i would look at is your roofing material. also with your vertical lines issue, what is the value for your camera's focal length, if it is a wide angle ( less than 35mm) that could be the reason for the odd angle.