Compared to smoking, it is. Obviously, the material itself may have a certain minimum level of smell, even before using in any device. With correct user technique, what the Box offers is no additional level of smell. With the right material and with a practiced user, the Box vapor can be very smell free.
Obviously, we strongly recommend that the Box user develop their stealth technique and test their progress with trusted friends before going out and using in public. Be responsible, do not take unnecessary risks, and be sure you know what you are doing before you try it.