Situated on top of a very steep hill (probably more than 45 degrees), i-House is a challenge to get to with a large suitcase or at the end of a long day of sightseeing. We were also in Room 405, which involves climbing another 4 flights of stairs (no elevator) but situated about a 5 - 10min walk to Myeongdong station, it's really not a bad tradeoff (and you get extra exercise for extra eating, if that's your thing).
You basically get exactly what you see in the Airbnb listing - a clean, minimal room with bed, mirror, mini-fridge and TV - all the essentials you need for a place to sleep in Korea and a place to put your suitcases. The guesthouse is a tall series of apartments on different floors, with helpful maps (English translated) on the walls and really lovely Christmas decorations that went up while we were there. Joon also sent us detailed instructions about getting to the destination and there were clear instructions and information about airport buses etc. It's these small details that makes staying at a guesthouse such a nice experience.
The room and wide bed comfortably fits two people and the heated floors are a godsend in Seoul's winter. I don't think guests can individually control the heating though, so it can get quite dry during the night. Also, the lack of windows means time can feel a little strange at times. Joon (our host) greeted us as soon as we arrived and helped us carry the suitcases up 4 flights of stairs (which is their own challenge). What's more is that there is a small kitchen on the top floor, with milk, cereal, eggs and bread provided, along with hot water, so you're saving the cost of at least breakfast if you use the facilities - fry up an egg, make yourself some tea and have some toast.
A couple of downsides - the bathroom is the main challenge as there is no divide between shower and toilet so it can be a delicate task to shower without getting your clothes wet (and always to make sure the knob is turned to the 'tap' setting lest you get an unexpected spray of water). Also, the sink apparently drains by leaking from the bottom, into the drain on the floor, which was a little odd and required you to position yourself away when brushing your teeth so you're not wetting your feet. Thankfully, with the window open, the floor was always dry by morning because a damp bathroom floor would have been very unpleasant.
Towels, shampoo, toothpaste and moisturiser was provided but there was no body wash and the towels are a little small - just enough to dry yourself off but not wrap around yourself or anything. Little details like clothes hangers were appreciated. We were super grateful for the hairdryer but there is only one setting: low. Be prepared to be sitting there for about 5 - 10min drying long hair.
The guesthouse owners have kept a very clean and well-organised apartment at i-House and we'd definitely consider staying there again, should we ever return to Seoul. If they can think of something to do with the bathroom, it would be almost perfect but, as it is, definitely good value for active travellers looking for a prime location to stay for a very reasonable price.