My wife and I stayed for 3 nights (including my birthday) in a floating tent at 4 Rivers Floating Lodge in mid-July. The location is very quiet as most boat traffic is on the other side of Koh Andet, and the occasional boats that do pass slow down to a crawl so there is minimal disruption to guests.
The floating tents look beautiful from the outside and are spacious, but they get very warm during the day as they have no AC, and the fans are insufficient to feel cool inside (the bathroom is particularly hot). The patio is a great place to moor a kayak or jump into the river (be careful if diving in, as the river height changes and is sometimes less than a metre deep), but it has very little shade other than a translucent umbrella, so it isn't a practical area to sit for a long time and lazily watch the river go by.
We found that the bed was quite uncomfortable -- there isn't enough of a headboard to be able to sit up, and the mattress is so firm that we both woke up with aching backs each morning, even after the staff added a mattress topper. While there is a safety deposit box, the tent door has no locking mechanism to keep other belongings safe. There is a small television that is hooked up to a DVD player, but there is no Bluetooth speaker.
We recommend that the staff roll up the flaps of the tent windows to allow more light and breeze in while guests are eating breakfast, as it is not an easy task to do alone. The breakfast is OK, and there is a reasonable variety in the menu, but the set dinners and cocktails are disappointing and overpriced. Guests should not expect to have reliable wifi service, as there was none at all one day, and there are no wifi extenders that relay the signal to the floating tents anyway.
Overall, we felt that 4 Rivers Floating Lodge was an OK place to splurge for 1 night, but could make a lot of improvements to justify its exorbitant rates. It is marketed as the premier eco resort in the region, but in fact our experience at a different eco resort nearby was much more comfortable and only a fraction of the price. Nevertheless, the service at 4 Rivers was excellent, and we want to commend Naran and Darong for being particularly outstanding in doing their best to accommodate the guests despite the resort's limitations.