I hesitated to pay for the course because of some reviews, but it seems that many people are satisfied when they are taught like an elementary school.. I have often felt that Ki-seon is a bit unfriendly when it comes to answering questions, but his voice is always nice during the lectures, and although he doesn't start the lectures perfectly prepared, I think that even elite developers working at Microsoft go to the lectures like this, so I think that even that is something to learn. I also think that just because there is a lot of content doesn't mean it's good. Sometimes, there are lectures that are extremely long compared to the price, but when you listen to them, they usually extend the lecture time by 20 or 30 minutes even though they could have explained it in 5 minutes like Ki-seon.. I haven't been able to listen to many of Ki-seon's lectures yet because I don't have time, but from what I've heard so far, I think they are all satisfactory for the price. If you want to see a lecture that teaches like an elementary school student, look at something else, but if you really want to learn the essentials quickly, I recommend Ki-seon's lectures. Everything I've listened to was good.