These all share the same problem. They're all flat, dull and uninteresting, and your over abuse of texturing everything is an eye sore. The colours are very washed over and bland, and nothing stands out in any way in any of them. Do not use decorative Photoshop brushes in real artwork. They are fine for logo's and simple decoration, but they never work in realism. The worst one is the grass brush. As for all original, I don't think so. The bird silhouettes I don't think are your original doing, and as for The Hills, the clouds are obviously not real. Don't say it's all original unless it 100% is.
As for no reference pictures, that is not a good idea. To truly understand these environments, go outside and take some photographs to help you understand them.
All negative? I really don't think these are that horrible. If you've seen his previous, he's shown quiet a lot of progress.
And actually, Photoshop is the LAST thing you would want to use for a logo. Since you are working with (bitmap) rastered images, resizing anything leads to it becoming slightly pixelated and distorted. Usually for logos you use a vector program, such as Inkscape or Illustrator. Vectors are rooted in mathematical expressions, so no matter how much you resize, your quality will always be nice, crisp, and clean. Photoshop can be used for photomanipulation (either the rendering of a completely new scene or just retouching) and digital painting. I do think its important to limit your use of the more decorative brushes and attempt to use your own painting skills, but it never hurts to every once in a while to throw in a few grass brushes or bird brushes. :)