It's very fast paced, sometimes to the point of the various incarnation arcs feeling a bit rushed. I think it probably needed a few more episodes but as is it means you don't linger too long in angst or heartbreak which keeps the tone up.

There is also a slapstick comedy aspect to it that I found it a little hard to get past at first. However, that slapstick element is mostly confined to the first third to half of each arc. As you move into the climax and later half of each one it transitions from cartoonish comedy to just the leads being playful and silly with each other.

The actors also have good chemistry.
I've heard some people say that the female lead wasn't as good as the male lead, and I'll concede that her acting in her tragic or melancholy scenes wasn't as impactful. But on the other hand she's really good at the playful, vivacious scenes and those are a lot more common in this drama. When the two leads are being silly and in love together they are a pure joy to watch.

Finally I thought their villain was very solid. Well written, with consistent motivations, a steady escalation pattern that convinces you he's a serious threat to more than just the leads, and a touch of humanity that made you sympathize with the characters who cared about him without ever making you feel bad for the villain himself.

Overall I didn't expect to like it as much as I did, but I really want to rewatch it again.


Edit: OH MY GOD REWATCH IT, YOU MUST REWATCH IT, IT REFRAMES THE WHOLE SEQUENCE OF EVENTS OH MY GOD I CAN'T BELIEVE THIS, IT'S SO SUBTLE BUT SO GOOD?!?!