This is one of those blatant cases where I can't help wondering why do they begin filming a drama when they haven't got the complete script yet? Why do they insist in making the viewer invest time and energies on something which changes from black to white in the space of an episode?

This is so annoying, and so sad.
Like everyone before me already pointed out, the lead actors did a brilliant job here. They are so natural together, it's a pleasure to watch them interact.
But even cute has its limit, at least for me. I didn't know of the writer switch until the last episode, but the difference was evident. What used to be a quirky, funny, sweet and sexy script suddenly turned into a sugary, childish, cutie cute one, with these two chirping to each other for the duration of six, never-ending episodes.
When mutual love has been loudly declared, the lie has come into the open, the antagonists are out of the games, what is left in terms of expectations? Who cares what they eat and when or how many times they hold hands?
Somehow, they used all their good cards at the beginning of the game, only to drag it with uninteresting little scenes till the end. By the third ice-cream I was ready to smear it on the face of the director.

Also, I was left wondering what happened to the majority of the characters? Were they sucked into some drama black hole, or sent en masse to Paris where they are happily eating escargots?

The music was somehow schizophrenic. At the beginning I though it was horrid, with those very childish pop songs used at every turn. Then it improved a lot, it became more varied and able to enhance the feelings. At times it was hilariously chosen. Then it changed again and became a simple background sound, which I forgot a few minutes after it was played.

Re-watch value is obviously low, unless something heavy hits me on the head and I think this drama's only got 11 episodes.