I recently discovered the potential of the Canon 50mm. Many people have told me it is the perfect lens for portraits, and I sure have proved it. It is amazing what you can do with a 1.8 aperture. The lens allows you to get to the right distance from subject so that they don’t feel weird, and not so far away that you miss their essence (in case you’re shooting a human).
Anyways, it is definitely a MUST for a range from mid shots to close ups. Either way, I think it is not the best for extreme close ups. It does not let you capture little details from a close distance, because it needs a minimum distance to focus. Neither for wide shots or landscapes. The perks of the 50mm is that the aperture allows you to play with the depth of field, or in a simpler language, with the blurriness behind the subject. At the end, it is good for emphasizing or driving the attention to a specific point in the composition. The rest creates and atmosphere in the back.