If I may, your pictures require from my point of view a little bit more work on texturing and lighting to stand out more. I would try to widen the range of colours you have in your final pictures (stuck between grey yellow and brown). For now it seems old and dusty. And you could also contrast your pictures with a more appropriate lighting, it doesn't have too be every day life lighting, photographs sometime use extra spots.
Could you tell us the render time and the type of computer you used for this images? That the kind of renders I would love to do but so far only in my dreams!
Thanks for sharing
-8Core (dual Quad core Intel Xeon E5335 processors)
-8Gigs of ECC Ram on a server motherboard.
-2x 512mb Nvidia Quadro FX 4500 with SLI (1 Gig Graphics power)
-Windows xp 64 (Which really kicks butt now with Maxwell's latest v1.6 Update)
Each rendering took about 22HRs to reach SL17 but that's because I was rendering 2 at a time.
I was in your shoes about a year and a bit ago. Stick with it and you'll get there.