I have stayed in bamboo several time over the past 5 years. As a couple and (f) single. I always returned inspite of the grumpy owners because the price is good for te location, rooms are spacious, It has a common area, drinks are cheap and so on.
Unfortunately, I cant recommend the place if you arrive late and rely on your booking. It happened the second time now to me that they claimed I didn't book. Despite having free rooms, the grumpy owner turned me down around midnight.
I have been to bkk 15-20 times, so I didn't stress but I certainly would if I was new to bkk.