If you travel abroad, you are in mood to go to restaurant with not only good food but good view. I usually go to at least 1 good restaurant using all my money when I go to other countries. Local eatery is fine, low cost local food is fine but you should try good food 1 time.
It is floating restaurant on Han river so it is not easy to find this restaurant. I used subway no4 station Dongjak and I recommend you to take taxi from there. (estimated taxi charge is KRW 3000)
If you want good seats with view, you need to make reservation first. And night view is better than day view. Italian food is good here with good price.
Desert is also very good. You should visit this restaurant on sunny days.