When using HDR, you have to be really careful with how a scene is presented. Landscapes really need a full dynamic range, including shadows. For me, the shadow areas are lacking, making it look unreal. This is another problem with HDR, I find that HDR photos look too surreal. That's fine if it is the look you're looking for, but it isn't something that is desirable in traditional landscape photogprahy. Also, when shooting water, it usually looks better to have some texture in rivers and waterfalls, although the misty look works well for coastal scenes. The textures help to emphasise the movement. Again, this is where shadows are important, to show the definition. Another effect of the HDR, combined with the ND filter is the overexposed water, turning it bright white with blown highlights. The HDR has also created haloes in the first image in the sky and the sky has also become overexposed. Personally, I would reduce the exposure overall by around one stop to give some shadows and recover the detail in the sky. Use of grad filters would also help to even up the exposure to bring everything back in range. As to composition, I'm not sure that the extreme wide angle works. The distortion has made it difficuilt to get a sense of reference to level the river and in the case of some of the images, there isn't a strong element to focus on when viewing. It works ok in the first one, but often with rivers, you need a strong diagonal to act as a leading line and the combination of wideangle and distortion has diluted that. Again, the texture of the flowing water would help here to draw the eye in. Many landscape photographers are used to getting wet feet or wear waders, as that way, they can compose on the diagonal much more easily. You do have to be careful not to end up floating down the river though. What I do like is the the texture of the leaves and trees, so if you can preserve that but making it look more natural, then it will improve the images greatly.
