I don't really care for the centered composition in this particular shot. The tree itself is interesting, but not enough to hold it's own in a photo. You might try to find something else in this area where you can include the tree as an element of the photo.
I really like the clarity of this image and the interesting sky and tree shape. I think the image could have been even more effective, though, if the tree hadn't been centred.
Viewed on a pc with ms ie.
Lovely clouds. The tonality range in the greens help give modeling to the various elements. The exposure is very good considering the difference between the lightness and darkness within the scene.
Composition. I think it could have been improved by getting closer to the subject. Most of the surrounding area is not interesting, so it isn't adding to the picture. By getting closer, you would have been able to cut out most of that and would be able to concentrate on the color, form and texture of the subject. I would have tried this with a vertical orientation.