Is Mister X worth hiring, despite mediocre stats, in Game Dev Story?
They get decent stats when their jobs are all 5's and had some training. You missed out on Kairobot as well, you can hire him after you get several game of the year (GOTY) awards. Mister X is one of the earliest special characters you can hire, his energy bar is usually way above any other employee at that time (meaning he rarely leaves the office).
You can train king and Mister X for less money; in addition, they have more energy.