Many believe that the only way to get a truly sharp image is to use a monopod (aka unipod). Unfortunately this is not true for everyone. Here are the pros and cons of using a monopod.
Cons: Monopods are fantastic but they add more weight to your already heavy camera bag. Unlike using a tripod, there is a much steeper learning curve with a monopod. It will take time to learn how to balance and best take advantage of a monopod. It's not a tripod and you still can't do long exposures with it. In other words it does not replace a tripod when it comes to stability.
Pros: It can often add stability especially if you are shooting a long lens or slightly long exposures. It can take the weight off your shoulders and away from your hands. When you are using a monopod you no longer bear the weight of the monopod on your shoulders or in your hands, it's actually resting on the ground. In between photographs you can lean the camera and monopod against your body or against a wall and reduce the stress on your back. All of this means that you will be able to extend your shooting day.