i was initially interested in this drama because i followed the leads and those actors were ones who usually didn't get main roles but when i saw that it was an idol-fan romance i instantly got the ick and abandoned it. the rumors of it being based on real life situation also didn't help much. now this is one of the most talked drama of 2024 so i made it a point to watch it and see what the hype is about. it certainly won't be bad if that many people like it right? i was wrong.
i would say the main reason why this drama was so successful is because it had pretty main leads who were down bad for each other. no proper/solid plot.

i was very creeped out by the fan-idol thing in many of the first episodes. the reason for her becoming a fan was genuine but her behavior was borderline obsessive. there were many times where she did things for him because she is a fan in 2023, which kind of creeped me out. also the fact that she was a 30 something year old in a highschooler's body chasing another highschooler was creepy to me.

my biggest complaint is how one dimensional both the main leads are especially sol. whatever we know about them revolves on the fact that they like each other. sun-jae likes sol but why? he likes her so much he is willing to die for her, what made him like her so much? i understand crushes but doing all this? in the first timeline it makes sense cause the accident is kind of his fault but after that? what is about her that he likes/loves so much? his whole personality was being in love with sol. at least taesung had a reason to like her. she was oddly mature with him and he liked that.
sol was so childish for majority of the show. it wasn't until the end she acted like an adult. during her first few time travels there was no difference between 30 year old her and high school her. she absolutely did not think before she acted.
so much of the comedy depended on sol making dumb decisions, it cringed me out. they could have shown sol and sun-jae better by avoiding all those cringy scenes between the brother and the best friend. sol got her ability to walk after 15 years yet it was barely acknowledged. she never seemed to spend time with her family nor her friends. same with sun-jae. u would think someone whose grandma lost her memory due to old age would be more emotional at getting her back. also how did sun-jae and sol end up in their respective careers. we don't see sol being so in love with movies nor sun-jae with acting. they could have given the characters more depth.

the time travelling plot was the most interesting part. the change in timelines and the effects they had were interesting. they were honestly what kept me through the series. even though the rules of time travelling and everything was weak it was nice. them being connected in every scenario was a nice touch.

the director/team could have just made a highschool romance with
Byeon Woo Seok and Hye Yoon and it still would have been a hit. they were the best parts of the show and did their roles well. them being casted might be one of the sole reasons the show is successful.
i would have preferred to have the idol fan thing out and make them like neighbors or something and not have the female be obsessive with the male lead, especially in the fan idol sense.