It is better than other box calculation software because it also considers approximate cabin gain, power compression, port compression and other non-linearity. Because of that, it can also predict final SPL in your car.
It is more useful because it knows how to handle total box volume in addition to net box volume. It can also calculate vented (ported) enclosures in the opposite way (e.g. it can calculate vent size or total box size for desired vent).
Projects can easily be saved and loaded. Boxes, Drivers and Vehicles can also be saved and loaded separately. Units an constraints can be changed under settings.
Please email me if you find any bugs or have any trouble. Quick guide is available on: http://www.pcmehanik.com/WBCGuide.pdf