I went with my family of 4 persons in total, staying at a family unit. It is very pleasant! We have kitchen and washing machine for ourselves, spacious beds, fast internet, TV, a window view overlooking the N Seoul Tower. Totally love it! What's more, the buffet breakfast was excellent, too! I especially thought the kimchi served here was very fresh and delicious, and even much better than outside restaurants' kimchi.... There is also a 7-11 store just downstairs at the hotel reception desk; we were surprised to find that the stuff there were not only so conveniently available but actually cheap.
Here is something that I think not many reviews have shared about this hotel. It's a 10-min walk from subway station, but we realized that the best (most efficient and cheapest) way to reach this hotel was to take the airport express train (AREX) (commuter version; 3300KRW/person only; 53minute ride from Incheon airport to Seoul Station) and then a taxi from Seoul station to Hyundai Residence (10-15min ride, ~6000KRW). Before knowing that, we actually took a regular small taxi instead and cost us 65000KRW, which was very expensive, considering that the taxi journey also took 70min, not really faster compared to AREX+short-distance taxi ride (Note: we took the taxi around 9pm, not much traffic jam at that time!). And I suggest that you show the hotel's address in Korean writing to the taxi driver and that will really help him/her inputting the destination address into the car GPS navigation system.
All in all, thumbs up for this hotel!