I don't think there is much science involved but there is no doubt that the proper utilisation of space has a calming affect. It is certainly no nonsense and has been used in home decorating for yonks, even before we knew of feng shui.
As with all Asian traditions that become popular in the western world, feng shui has blossomed into a profitable financial commercial business and has been so adulterated to appease the customers that it has a diminished resemblance to the original custom.