You always have complete control over how much resistance you place on your muscles. You'll never over, or under, load your muscles.
The static nature of isometric training spares your joints from the abrasive forces involved with heavy dynamic training.
Typical isometric workouts can be completed in a fraction of the time of dynamic workouts. 5-10 minutes is plenty of time to work your entire body.
Isometrics quickly teaches you how to synergistically generate a lot of tension throughout your whole body. The better you get at isometrics, the stronger you become at everything.
Isometrics doesn't create the stress and strain of dynamic training; so you can push yourself and be ready for more in no time.
You don't need to be a gifted athlete to push your muscles to their limit and beyond.