Creatine is one of the safest, most researched, most effective strength boosting supplements ever for exercises that are high-intensity or explosive. It is found naturally in meat and supplementing can make a big difference in your output and recovery.
One thing is almost certain: If you take creatine, you'll gain weight. At first it will just be a few pounds of water weight. Creatine pulls more water into your cells which then increases muscle synthesis, then it will become more more muscle mass due to the increased workload you can handle.
Here is a summary of the benefits: