Hey swifaw,
This is a nice picture. From a technical standpoint when shooting a vast landscape such as this at the widest possible focal length, you might want to stop down the aperture. Landscape images tend to enjoy the f/8 to f/11 apertures the most, and keeps parts of your picture from being out of focus due to DOF issues. Also, when shooting landscapes, it's generally a good idea to minimize your ISO speed. While 400 is good on a Canon SLR, the image would be much cleaner at ISO 100. Another thing you might want to consider is that the bank on the opposite side of the river is a bit crooked. If you rotate it just a couple of degrees CCW, it would be much better.
Composition-wise, your images need a bit of...je ne sais quoi. First off, the rule of thirds is important, and even more so when shooting landscapes. In this case, the bridge would be much more relevant if the horizon was either 1/3 or 2/3 of the way up (i.e. more water or more sky). The fact that it's in the middle makes the image a bit flat. Secondly, I would have done a little more to make the boat the focus of the image, by either zooming in a bit, or perhaps waited until it was more in relation to the bridge. It is essential to have some sort of a subject when shooting a landscape in order to put your pictures in context, and allow them to have a voice. This simply takes practice, and some thinking before you snap the shutter.
Overall this is a nice image. Keep it up.
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