Pull-ups are a staple in my own training as well as all my clients and athletes. I think we can all agree that they are wildly beneficial in so many ways. Building up one's relative strength is key to improving overall strength, as well as producing force, being explosive and in the long run, helps body composition. (When your relative strength is high, you can do more body weight things, and do them better, giving you more options to improve you body comp.)
One big mistake I see with pull-ups is internal rotation of the humeral head. When this happens, you're not fully engaging the lats as they should be. (It also happens in incline pull-ups, inverted rows and even lat pulldowns. Lat pulldowns are easier to adjust as you can lighten the load to the person's strength level. Lightening the load in pull-ups requires bands or a partner, but can still be difficult to lighten it enough to do the movement properly.)
Here's one variation I love doing with my beginner clients! Watch this video to see where you can improve your pull-ups!