The staff was very friendly and i always had fresh towels in my room. There was mold in the bathroom around the sink and in the shower which was a little offputting. I appreciated the fresh towels, but just a heads up, they're small. I needed two to dry off.
I got an oceanside view lime i requested, but there is a building's being built directly in front of the ocean view so it kinda blocked it a little, and construction stated at 5AM every morning.
Another thing to keep in mind is the location. GRIM resort is very close to the the airport and directly in the flight path of incoming aircraft, and they come CLOSE. Construction will eventually end, but the flight path will always be there.
Overall it wasn't a bad stay, it wasn't expensive and you get what you pay for i guess. I spent only spent my time in the room showering and sleeping at night, oh! I almost forgot! There are fishing boats close to shore that sound off loud fog horns or something at night. So yeah, if you're coming to Jeju to sleep in and stay in your room all day this may not be the place for you to stay but if you plan on starting your day early and coming back late-ish you'll be alright here.