The hotel staff is excellent, very helpful and courteous but can be overbearing as they tend to hover a little too much. This is typical of Koren style hotel staff and is nice for a while if you're on vacation but when there for business or work at DSME can be tiresome.
Korean food is good but after a while if you want something Western style don't expect much. There are plenty of decent restaurants within walking distance though and lots of expats if you don't speak Korean that are usually friendly and will help you out.
There is a seedy side to Okpo though so be careful what bars you head into unless your looking for that sort of thing.
Book a higher end room, I was there 3 weeks this last time and had to extend my stay at the last minute, was moved from a deluxe room with a queen bed and working heat/AC on the 3rd floor to a single bed room (essentially a cot) on the ground level that was like a sauna, AC didn't work so had to sleep with the windows open.
It was the only room available according to staff but I was charged the same rate as the rest of my stay. All the credit goes to the staff though because I could not fly and needed a room, in my experience it's the best hotel in Okpo and second best on Geoje Island, only Samsung Hotel is superior but overpriced.