Delicious! I've been multiple times, and tried both the Combination Soon Tofu and the BBQ Grilled beef dishes. Both amazing and exploding with flavour, but I definitely prefer the combination soup the best.
On top of mussels, beef, tofu, and other goodies, the combination comes with an egg that you crack and get to watch cook in your soup (and eat it too)! This is also comes with delicious purple rice, along with Kimchi, and other sides.
Be prepared to wait 15-30 minutes on weekends and on popular (Friday) nights, as the place is quite popular and doesn't take reservations (and as thus, is quite loud).