As an HDR exercise, there probably wasn't much for Photomatix to do. I suspect you pickup up the details in the distant hills, but other than that, the range isn't that wide and the edges are soft. It would be interesting to see the 0EV photo for comparison.
Compositionally, shots like this suffer from the light foreground. Whenever you've got light objects in the foreground and dark objects in the distance, the scene looks flat. I think you probably had to choose between a 'near-far' composition that moved the horizon up (and emphasized something in the foreground), or a 'big sky' composition that moved the horizon down (and emphasized the sky). The intermediate composition, while an accurate portrayal of the scene, isn't as interesting.