I think he is famous for his incredible teaching style, I am not a civil service aspirant then also I have watched almost all of his videos that are available on YouTube, Concept talks is my favourite, I recommend you also to watch them.

Some of the qualities I have noticed so far includes his great style of teaching and unique method clearing concept of complex topics, great sense of humour( you will never get bored of his teaching) simple living, humble nature and his love and support for hindi medium civil service aspirants.