What's up with all of the noise in the image? It may obfuscate imperfections, but it's difficult to rate with such degradation in the quality.
From what I can see, the water looks to be a little bit flat; ripples and waves would make it look better. (Also, does the reflection match the sky?)
As for the grass, you may try some alpha to coverage and make it stand up rather than having the "blanket" grass referenced above.
The sky gets a little weird towards the spot where the sun is coming from. I'm not sure if it's perspective or quality that causes it, but it's just weird.
Keep it up!