Well damn. This is just great. Have you seriously been composing for no more than a couple of months? In that case, your skill level must be extremely high! I havn't heard the first version, but what I know is that this one is stunning. And not only that, it captures the theme of the picture SO well. Do you know what this reminds me of? Have you ever heard about Gustavo Santaolalla? He made music to the movie "Amores Perros" and to the game "The Last of Us". I'd say that this style is similar to his, in a very good way.
I think the panning might me a little odd, but I don't really see it as a problem. I like all of your instruments too, as well as the nature sfx. Immediately when I heard the guitar in the beginning, I knew this was going to be a great track. Especially 1:04 is a highlight, since the drums enter. What free sample library did you use for this, I'm interested to know?
All the strings are amazing as well, not to speak of the melodies and the atmosphere. I know you said you wanted brutally honest reviews, but honestly, I have nothing I really feel like complaining about at all. Even the structure and most of the mixing seem just fine to me.
Once again, the artpiece that inspired you is simply great. And since you were searching for a post apocalyptic theme, which musicwise was extremely well done in "The Last of Us", I'd say you managed just great, as the style in this piece is similar to Gustavo's!
I'll look forward to future stuff from you, and I'll probably check out some of your older stuff as well :D
Good luck in the contest!!!