Usually, this is not my genre (the show is a bit on the horror side and, except for vampire stuff, I get scared quite easily), but I was so attracted by the cast (I love both So Ji Sub and Gong Hyo Jin) that I decided to give it a chance.
The show is overall lovely, although in my humble opinion it drags itself out too much.
So Ji-Sub and Gong Hyo Jin are simply amazing together, all my stars are for them. They really have great chemistry but, most of all, they're so good. The same story acted by someone else could've been much worse, but they can make any plot believable and enjoyable.