It's not an AMP. It's a Korean bathhouse.
It's enjoyable, but not in the AMP sense of the word. I've been a few times. When you go in, you remove your shoes and head to the locker room. If you like you can choose to go into the wet room - an area where there are showers and pools of various temperatures of water. It's not coed...and it's segregated by gender.
If you choose to go the other route, there are rooms that are coed. These are dry - but also of various temperatures including one you could likely cook a turkey in. There's a set of chairs for watching movies as well as a "snack bar." If you're in the dry area, you wear the clothing issued by the spa. You can stay there for 24 hours for less than $20.