I like this hot. A few comments:
1-Exposure: this shot is very well exposed. There is a great range of tones from highlights in the sky to the dark trees and you managed to retain details in both. Good job.
2-Depth of field: again good job on the DOF. The image is sharp from the rocks in the foreground to the mountains in the background. A shallower DOF would ruin such a shot IMO.
3-Composition : I quite like the composition of your shot. There is foreground interest with the rocks, then the greens of the lake and finally the trees, mountains and sky in the background. However, I think the composition is a bit unbalanced as the rocks add a bit too much 'weight' to the lower left corner. Maybe you could try to isolate a single rock in the foreground. What do you think?
4-Suggestion: I think the use of polarizer could maybe improve this image. The reflections in the lake are not very interesting (mainly white reflection from the sky); the use of a polarizer will decrease the amount of reflected light on the lake thus bringing out the green colour of the lake. This may also intensify the blue sky.
Thanks for sharing. Your shot reminded me of two beautiful weeks I spent in Jasper and Banff national parks a couple of years ago. If you have the opportunity, go back there: there are so many beautiful landscapes to shoot in and around Jasper.