There's a slight monotonicity rockin' that there tree-line at the back which isn't too groovy.
Likely some height variation or size variation might do it good.
I'm also not sure I'm digging the intense whiteness of the river splashes, even though
I know they can't be tinted, they still kind of crash with the overall... Soothing nature
of the terrain. Loving the sky, though, and even though I think you could've added a
little more fading light, to give the terrain a dash of more vibrant colouring, I will say
that the alleviating aura that this terrain gives off is... Alleviating.
Oh, and, yeah, the bridge could use some love.
Those textures looks mighty stretched.
And, I don't think it'd be a horrible idea to sink some of the foreground
flora a tad into the ground, so it doesn't look like every piece of grass
spouts from exactly the same point of origin.