Pailin House is run by a lady by the name of Pailin. I've stayed here a couple of times now and the place has proven to be reliable and good value-for-money. It would probably have to be classified as a guesthouse, and prices have been around 400THB for a room in high season and 300THB in low season. They have bungalows available as well for slightly more, but the photos you see are of one of the rooms (except the photo from the riverside which shows some of the bungalows). Funnily enough I stayed in the same room each time I've stayed there!
The owner is a friendly lady who speaks OK English and runs Thai language classes for a small fee. She used to be a teacher and advertises times for her classes but I daresay they are easily arranged "by appointment". Friendly, hospitable and a great ambassador for Pai town!
There are other guesthouses available in the area but I like the relaxed unpretentious atmosphere at this one. My bedding and room was always clean and for the price, I got a room with TV, fan (Pai's climate is usually pleasant enough to survive without air-conditioning), shower, bathroom, toilet, free tea/coffee and 2 bottles of drinking water per room per day.
The town is about 5-8 minutes' walk from Pailin House, and with some of the unusually high prices being seen in some of the resorts in Pai, I certainly recommend this place if you're not looking for classy upmarket expensive hotels. The only real gripe I have is that it was a bit of an involved process closing the windows in my room, having to open up the flyscreens to get to some of the window "doors" to pull them shut, and there is little sound insulation. So if you're an early riser that's fine, but if you like to sleep in, then take earplugs to block out the noise of the birds and other animals in the natural surroundings around this place.