For a minute there, I thought I'd pulled a pic from the sign challenge :) I had a lot of trouble finding anything square and ended up creating something. There just aren't many square things around, but you found one! Nice work. Unfortunately, I don't think it's the most exciting or interesting subject for a photograph. I do like the composition - how you have it centered with equal amounts on either side. I really like the shadows and grass in the bg. Nice use of dof. I'm not sure what created the little bit of shadow at the bottom left corner of the sign, but it's a little distracting. Overall, this is very good technically. Good focus and exposure. I really like the texture of the rusted metal. I think you can take good pictures. Now that you've got that out of the way you can focus on creativity and come up with some shots to wow everyone.
I like the shadows in the photo, and the concept of something old and worn. The rusting adds nice color. I think that maybe this wasn't the best idea for photographing something square. Be more creative.
I would normally say "too centered" here, but the girder splits the image up nicely into three distinct textures which I like a lot. Could have done without the shadow on the bottom of the girder, but that's the only fault I can find. Great shot.
The shadows on the left and the dead grass on the right are very distracting. You should have zoomed /cropped this more closely to exclude that other stuff.