I also took Udemy John Thompson's lecture, and I found Younghan's lecture to be very helpful because he inserts practical tips here and there. Rather than a lecture that simply lists usage or grammar elements, a lecture that conveys tips that are often used in practice can reduce the learner's worries. I recommend it to JPA beginners or those who do not have much experience. Also, from the learner's perspective, if the instructor teaches in a somewhat cold(?) manner, it can feel psychologically distant and make you not want to listen to the lecture, but Younghan's likable and friendly personality is also a big plus.