I would recommend this drama solely because of the excellent acting portrayed by Jeon Ji Hyun in her role as Cheon Song Yi. Cheon Song Yi is one of the most lovable female characters I've watched. She presents an abrasive personality initially, but demonstrates a strong sense of respect for herself and her loved ones, with a somewhat innocent (and thoroughly amusing) side when it comes to the man she loves.

Do Min Joon is a very old man--well, really he is an alien who has lived for many years on Earth but because of his alien lifespan, he still looks as young as ever. Kim Soo Hyun does a decent job in this role. Do Min Joon provides a good contrast to Cheon Song Yi's overflowing personality.

The side characters are what you'd expect from a kdrama, but they play a satisfying role in the story and are not lacking.

"You are my destiny~" I have a feeling this song will become one of those iconic romantic kdrama songs--the kind of song that starts playing at the beginning of any romantic scene, meant to pull at your heartstrings. For me, the song is very cheesy (but hey, it is a kdrama), but I think they were successful in using an iconic song that will be immediately associated with this drama as I heard it playing throughout Asia, months after the drama had finished airing--this was definitely a huge hit when it aired.

Despite certain flaws in explaining the alien element, I would still definitely recommend this if you're looking for a fun romance with a little bit of drama, as the main characters will keep you entertained for the whole show.