Well, no need to be gentle; you did a really fine job. The lighting is perfect, waves seem ok for this lake, trees are nice. I like it. Next step might be to work on the foreground, like on the waterside area. You might want some fake stones there, maybe a little sandy beach here and there. Lots of fake stones setups to be found on the forum, just add them and mask them by distribution shader set to a range of the water height. Work on from there. Do put the reflective shader (noRT) under the stones, so they effect the stones.