First of all, the story is a bit silly but it made me so happy while I was watching, I smiled a lot just seeing those characters with funny and cheerful personalities. It develops smoothly, I really enjoyed watching this. The special effects aren't good though.
I loved the cast. I had never seen Park Bo Young and Park Hyung Shik before and I fell in love with them. They were perfect for these main roles, the rest of the cast were good but not as good as them.
The music really fits this show. You hear it and you immediately associates with this drama.
Since I had so much fun watching this, I'd really love to rewatch it.
SPOILER
Lastly, there's just 1 thing I would change about the story. It broke my heart the fact that Gook Do ended up alone, so this is the only thing I would change.