- bad photoshop skills,- things like this
make it abvious that you just used the magic wand- some of it is rescaled and looks pretty bad.
Better render it out with a clean alpha channel and dont scale it up in photoshop.
- thumbnails have distorted propertions
check out the crop tool in photoshop to do it propper
- to much different typo styles,- and bad placement, for example in this picture
the text "Spec" is to close to the texture- and the "Modeled UV´s & Textured" is a completely different typo. Also the former font is that Times New Roman?- if so worst choise of all
maybe a sans serif font so it looks a little bit more serios, have a look for free fonts at:
many of the 3d models and textures are fine but the website presentation is bad,- and that´s mainly because of typo, proportions and extraction techniques- to sloppy in my eyes -your work deserves better.