Everything about this series was beyond amazing! The acting, music, editing, and special effects all of it was done so perfectly! Especially the editing, they did such a phenomenal job with the transitions from young to old! I loved the original movie, but this series was leagues better and I already want to watch it again. Though I had to buy a copy off ebay to see it with english subs, it was 100% worth it!
The only thing that brought down my rating a little, and only a very small amount, is two things.
First, Ji Hoon grew on me but it did start to get on my nerves how much screen time they were devoting to a couple who wasnt going to be endgame anyways. By the end of the series I felt so bad for him that his feelings weren't reciprocated ? Second reason is, I feel like the kids should have been told. I get that it may have been awkward and they may have gotten angry, but they deserved to know. Especially Siwoo who was extremely close to Woo Young. I get he made the excuse of going back to the states, but in this age with cell phones that wouldn't explain no contact. Can you imagine how heartbreaking that would be for Siwoo. With Woo Young being his first and best friend, to all of a sudden not ever being able to talk to him again, with no real explanation.. He wouldnt understand and would probably think he did something wrong. I know he became friends with the basketball team, but I dont think that would've been the same as his friendship with Woo Young.

Overall as I said, this series was beyond amazing! Its a 9.5/10 for me!