"Bamboo" fabric is made from viscose rayon, a synthetic cellulose, with the bamboo canes chopped up and chemically processed in the same way as any other source of cellulose. It is considered "green" because bamboo is considered more sustainable than traditional wood sources. There is no real bamboo left in the fabric itself. Same with "hemp" fabric, hemp is just another source of cellulose.
Rayon is a soft fabric: the synthetic cellulose can be spun in very fine, silky fibers so you can get a very high thread count. It is as prone to staining as cotton, but is less tolerant of either chlorine or peroxide bleach. The sheets will arguably be less durable than cotton in a B&B setting.