Positives:
The room was very clean.
The bed was very comfortable.
Location is right in the middle of Seomyeon (a popular commercial district).
The price is very reasonable for what you get.
Negatives:
A bit dimmer than expected (in the pictures the rooms look like they have a lot of light, but this room had one frosted window that faced a brick building).
As another review mentioned, they offer a free night if you give them 10/10, which I really don't like, and makes me feel like I can't trust other reviews.
The place is rectangular, with all doors facing the central atrium, which doubles as the reception area and kitchen. I'd say, as well as lacking the amenities of a hotel, this place lacks the social aspect of a hostel, partly due to this.
I'm not sure if it's usually like this, but I could still hear music from nearby bars at 1am on a Monday (though not very loudly).
That looks like more negatives than positives, but all the essentials were there, so my overall review is good.
This place is definitely a decent option.