It was amazing. It had not too much Drama, so you were able to enjoy it even after an already draining day and the two main character somehow perfectly matched with eachother.
I also liked, that the drama was not focussed on fighting between the main characters, but instead on everything around them.
I was a bit sad that they seemed to rush the last episode a bit, but it still was rather enjoyable.
I'd totally recommend this Drama as a first, because the topics are not that heavy and while the main female character sometimes backs away from hard stuff, it doesn't make her weak, just like it is in reallife. I also enjoyed that they both had strong and weak spots and that they were shown.
For enjoying this drama, you should be open to a bit of fantasy, because some scenes are about the online game which is mostly based on fantasy.

[SMALL SPOILERS FROM HERE ON]
She loves to game, but is not suddenly a pro in programming so she's able to help him make his game and he is very clever, but has a soft spot for his friends and he's not very good with normal chores.
Their friends somehow all have their own characteristics and you can fall in love with them just as much as with the lead figures. Sometimes I couldn't wait for Nai's friends to be in the scene too, because they gave the whole story a much more fun twist.