Ask yourself one question before you come here: Would I enjoy an outdoor experience like camping? If the answer is yes, you will like it here. In the middle of nowhere on the river, removed from civilization, it is hot during the day and gets cold at night. It's actually much more comfortable than camping because you have a nice bed, bathroom, and restaurant. I'd recommend bringing your own flashlights (the room is very dark), batteries for electronics you use (without internet, obviously, 3G signal is also very poor at the hotel), and ice (to keep stuff cold). If you can't do without the electricity, definitely still stay at their sister property, Float House. You won't regret it.
A couple small complaints I've seen in other reviews: It's true the staff isn't super-friendly, rooms are small, and the bathroom in our room smelled bad. Also be aware you have to arrive at Phutakien Pier before 6PM every day to catch the last boat.
Complaints from other reviews I found not be true: Very few boats passed by our room because this is the farthest river hotel from the pier, and we were in the last section of the hotel. It was very peaceful.