I didn't think a lot of people liked it that much at all. I may be in the minority instead. I don't think it's a spectacular series, but there are charming moments. David Henney was sweet but even then his character was contrived since they wrote it especially for him after his audition for some other role and thought his acting was unique. The lead while not making as huge an impression as say Yon-sama actually does a great job for a new actor, which I am quite impressed with. There are some inconsistencies, in the way that Yeena still wants to marry Jae Ha knowing he's not even the same person. She didn't even feel he was the same boy she knew as a child and still wanted to marry him? That's just weird.
Story-wise Korean dramas are not known for originality. It sticks to a known formula that works. I really hate sad endings, which is probably why this drew me in more than the other Season dramas. I still don't get the fuss with Winter Sonata. The story is still as cliched and I thought while Choi Ji Woo and Yon-sama were reasonable as adults, the high school scenes just weren't convincing. They were too stiff. At least in Spring Waltz they just used child actors and the couple scenes were quite charming, though repetitive, in adulthood.
I'd give it a 3/5. I do think it deserved better ratings though. Given that it aired as the final instalment of the Seasons series I thought it had a comparative disadvantage in the first place. How many variations of childhood love stories can you get? I did love the scenery in Austria and Cheong San Do though.