Just finished this up for the BlenderGuru “Saying Goodbye” Competition.
Full Resolution Image (~3.27MB)
Blender 2.61
Cycles - 1000 Samples
Textures - Custom + cgtextures
Great idea and nice rendering. The small particles for dirt is excellent, the DOF is perfect!, the realism is 90% there. The shoe lace texture is perfect but they are a little too flat against the shoe. Look at a real shoe and see how they aren’t so perfect. The blue/grey shoe material looks a little too perfect. Maybe increase the size of the texture by 50%. The stains on the shoe are not real looking. Maybe add some wear to the material. I would get a real cloth material from CGTextures and use that for the shoe material. The shoes sole is amazingly realistic but the scuff marks on the rubber sole aren’t convincing IMO.
Also, it looks like the person is stepping “over” the bug instead of going to step “on” the bug. I think your intention may have been to make it look like the bug was about to get crushed. If this is the case then it would look better (more realistic) if the foot were on the “heel” instead of the toes and the bug was under the front of the foot.
Really excellent image though and with a few tweaks I think you may have a winner!
I completely agree with Paint Guy. I think the shoe looks the most fake in the entire scene; it is too clean.
That’s absolutely awesome! Very nice idea and well executed too… 
Very nice work!
A few things:
Put some stitching on the shoe! I’m wearing chucks right now, they have contrast stitching next to the laces and near the toe. You also need to have more realistic creasing where the toe bends, and you seem to be missing the finer knurling on the rubber around the sides and in front.
Otherwise, this is quite good. The shoe needs work, but this idea is very nice, with more detail on the shoe, I think you could do well in the competition. Love the idea.
@Paint Guy: Thank you for your comments. The shoe was an absolute pain. I know it detracts from the scene. I kinda got to a point where I had to say enough and just submit it to the competition. I agree with your suggestions for the most part - though I’m not too sure how increasing the size of the shoe texture would work out. The reason the shoe is at the angle it is, rather than on the heel is because the scene was originally going to have the shoe coming up from the already crushed roach. When I changed it to the live roach I decided to leave it as is because of the amount of work involved in switching the angle (the shoe is not a complete model).
@Kemmler: Ah yes, the stitching. I spent a couple days on that about a week back. I gave up the idea after attempting it. I want to blame it on my imperfect UV unwrapping, but they just wouldn’t come out right. Due to the time limitations of the competition I decided it was in my best interest to move on. As for the creasing, I agree. I should have spent a little more time on it. Actually, what I should have done was model a shoe I actually own so I would have a better reference. . .
I did stitching on a shoe once, I actually just modeled it out using dupliverts or something. Brute force method!!