I've became interested in this drama after seeing some scenes but with no idea about the whole story.

The story is completely not credible.
First, it spans over 5 to 7 years (it starts when they are in high school and at the end they are working professionals, who have completed their studies in engineering and medical school).
They are about 18yo when it starts and let's say 23-25 at the end.
The main couple interaction stays at high school level almost till the end... their characters don't really change over this period of time. I mean, I can accept she's shy at 18 but not at 25, it's just ridiculous...
The ML liked her since he was a kid but he only confesses when he's 20 something... And the FL takes all this as granted.
But then, that's Chinese drama !?

Also, the FL is supposed to be very good at what she does professionally but she's just stupid when she's shown some evidence about what happened to her parents/foster parents in the past - she takes it all as it is shown, never questions, even if it comes from her enemy. It takes some episodes for her to start thinking there's something fishy...

The antagonist also behaves as a stupid brat, "I've always had everything I wanted so I'll have you". It goes like this for years and in the end, 180° turn - after throwing a tantrum like a 3yo she suddenly realizes it can't be...

The other aspects, like their professional lives, are more or less credible... you go through medical school and training for years (I assume it's not easier in China than in western countries) then you end making cakes? I respect all professions but they could have given her a research position (which was said she was good at) if she can't stand losing patients.
The ML wins a prize for his robot and transforms the award ceremony in proposal?

What I liked - ML and some of the scenes with FL. Some said he was too cold - I see his character rather as someone who doesn't know how to behave and for this I found him touching. He always had one thing in his mind, since he was a kid - and that was the FL (which I find spoiled and immature in this relationship). He completely lacks any sense of humor. He shows some changes in the end, he becomes more careful for other's feelings. There were also some funny moments (ML dancing...).

Also, 2nd couple seems more natural - I won't point what I found not so credible.

That's all I've had to say, I would recommend it if you have time to spare. I generally watch dramas at 1.5 speed so I can't really appreciate the OST.
As for re-watching, perhaps some cute scenes, but definitely not all of it.