Nice. It is a very pleasant image.
I agree with Tim that it is kind of a "two images in one" composition. There is nothing wrong with capturing an image of the whole scene, but tighter crops on either half of the waterfall might produce stronger images.
And I agree with Vegematic that ledge in the foreground is a little dark. The scene might be improved with a split neutral density filter. This would allow the foreground to be brightened and the background colors to be darkened/saturated. The exposure contrast between top and bottom of your image is not far out of balance, and many might deem it quite acceptable as is. A one stop split neutral density over the top might be all you would need.
I have attached some images to illustrate two other easy things that could be done to improve the photo. My scenes are nothing special, but hopefully they exemplify the points. You can click on any of the images to see larger versions.
Polarize. The bright glare of the reflected sky on the water in your foreground draws attention away from the waterfall. A polarizer filter can reduce and potentially eliminate the glare on the water. Below is a comparison of unpolarized (left) and polarized (right) images of the same scene. I had the polarizer filter on the lens in both cases so that the shutter speed and aperture would be the same in both images, and dialed the filter to its minimum and maximum amounts of polarization:
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Set the White Balance manually. Your image has an overall blue cast. This often happens with photos captured on an overcast day and in shaded forest scenes. Most likely you are using the Auto White Balance, AWB, of your Canon Rebel XTi (400D). The AWB is supposed to read the light quality (sunlight, shade, or overcast), and automatically adjust the color balance. I have found that this automatic compensation to be unacceptably insufficient, and/or ineffective. Here is a comparison of the XTi's AWB (left) and Overcast white balance (right) settings on an overcast forest scene:
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I consider the colors in my AWB image to be unacceptably blue. The overcast white balance image is far closer to what my eye and mind registered in the field, and it is far more pleasing when viewed at home. Since discovering how bad the AWB is I now never use it, other than to capture an occasional comparison to demonstrate how atrociously bad it is. Yes, it is one more thing to remember to set properly, and of course it can also be later adjusted in Photoshop or another software photo editor.
All 4 images above were taken using the "Landscape Shooting Mode" to improve saturation, and all four are straight out of the camera without any additional photo editing.
