How does the feeling of the landscape change when it's cropped in a very tall, portrait format? The farmland is interrupted by the town, then continues behind it, but instead of stretching into the distance, creating a feeling of space, it is ended by the mountains. Overall there's less of a feeling of space and depth, but the tall format does add a sense of grandeur and height to the mountains.
As you can see, using a viewfinder helps to focus your attention on what would be in a specific composition by framing a specific part of a scene. What you ultimately decide to use will, of course, depend on your personal likes and dislikes.
