It's not great value for your money. The staff seems somewhat rude, as if they'd rather be anywhere else. Then again this is the impression I've gotten in so many places in Cambodia and SEA, I guess it's just a different kind of customer service they have here.
I was ill and tired when I arrived, so I just walked to the first guest house I found. Location of Koh Pos GH is very nice. I got a twin room for myself for $25 a night. I think it was a bit too much. The room was big, bed comfortable and had hot water. There was even complimentary tooth brush and paste. But that's about it. No one said a word about breakfast, so when I went asking for it in the morning, they told me it had already ended. This was before 10am.
I didn't greeted when I arrived and check-out was completely wordless. No thanks or byes or anything.
It was allright for a night to recover, but I wouldn't go back.