Flaws in your squat technique will hold you back from progressing. Overhead squats can improve the squatting pattern and should be a regular part of your strength training program.
The overhead squat requires a more upright posture than the back squat and you're forced to execute the squatting pattern precisely, otherwise the bar would drop to the front or back.
Have a look at the video. You can see the high concentration level of the athlete and accurate execution.
If you want to correct a few muscle imbalances you may have created before you knew better, or if you want to fortify the integrity of your shoulder joints and maybe even improve your posture, then this might be just the article you need.