Peter,
This is essentially the criticism I get, they look false.
All "IMO!"

I must admit the first (mountains reflecting in lake) isn't too bad, but it still stands out immediately as 'not natural.' The reflected image needs to be darkened, to match the real-world reflectivity of water. I also think the middle tones (forest around mid-picture) are somewhat muddy and indistinct. I'd re-set the black level to drag the darkest forest tones down a stop or so.
The tonal scale for the second (the waterfall) is, IMO, completely whacked.

The snowy mountains are somehow no brighter than the foreground foliage? The HDR process created a situation where the quality, brilliance, and apparent direction of the light is mismatched - the viewer's eye sees this and says, "Huh?!" Overall, it looks for all the world like a poorly merged composite. (something we've all seen way too many of.)
The tonal characteristics of the are close to looking natural. Perhaps the basic composition is a bit too bi-polar.

The colors, textures, shapes, etc. of the mountains don't seem to compliment or otherwise 'communicate' with their counterparts living in the trees. IMO, you need to establish some sense of continuity between them. If you could find a place where the shape of the trees mirrors that of the mountains, you'd have that 'bridge' that allows one half to relate to the other. Or re-compose to show a river flowing between them, etc. If I took this, I'd put it down to "Well, that didn't work as well as I'd hoped."