This was my first stay in Seoul and I loved it. The manager was kind and generally around during check-in hours if needed.
Each floor has trash and recycling areas, used towel bin, and a clean towel cupboard. A shared kitchen is on the 4th floor with just about everything you need for simple food prep including a microwave, cook top, microwave, and water dispenser to refill water bottles.
Rooms have room and bathroom slippers, a small desk, closet with a mini-fridge inside, and compact wet bathroom. If you haven’t travel to S Korea or many Asian countries before, the bathroom and towels might be an adjustment. Do some research on how to manage. It’s a little more effort than western bathrooms but practical and truly not a big deal.
As others noted, the walls are paper thin between rooms, and during check in guests are asked to keep it down, but you’re at the mercy of the other guests courtesy level. I travel with earplugs and noise cancelling headphones, so it was fine for me.
The location was great for restaurants, wandering the area, and for accessing buses and the subway. I could get just about everywhere I wanted to go on one bus without transferring (I prefer buses so I can see more of the city, but the subways are fantastic too).
I would absolutely stay here again.