I booked the Premier King Room. Check-in and -out was smooth and fast.
Cleanliness: Super clean, loved it!
Location: 2min above-ground walk to Yeongdeungpo Stn, great! There is a small convenience store in the same building (not connected from the inside) and it has kimbaps, sausages, cup noodles etc.
Size: It was good for a solo stay, but if you intend to stay with someone else, it would've been a little squeezy. There is only enough space for one luggage to be left open. I did love the room design though, very creative!
Amenities: No conditioner, toothpaste, toothbrush, or shower cap! Bodywash, "conditioning shampoo" and hand soap are in bottles bolted to the wall rather than sachets. They do have (very thin) room slippers and bathrobes though. 2 packets each of green tea, coffee, brown sugar and white sugar are provided with the usual mug, spoon and 1.5L electric kettle. TV has a lot of local channels and you can access Netflix, Disney+ and Youtube. The full- and half-body length mirrors are really good for fit checks!
Noise: My room was on the 8th floor and faced the train tracks. The trains rumbling by every 15min or so is noticeable, but not loud enough to be shocking. You do get used to it and it did not affect my sleep. Either the walls are good or my neighbours were considerate, but I could not hear the TV/voices from next door.
Overall - I enjoyed my stay very much and would be happy to rebook!