I really like the concept of Soft Soap, but the props you're given are difficult to use. Its
probably worth the money, but you may need to "re-do" some of the stuff you get.
A lot of magic is like that ... you have to re-build or customize it in some way to bring it up to professional standards.
The Soft Soap "plot" still works , but one thing I would do is make high-quality scans of each panel of a real detergent box like 'Arm & Hammer Laundry Booster' or '20 Mule Team All Natural Borax Laundry Detergent' (two of the remaining brands that still market in traditional style detergent boxes) , then take those scans into Photoshop and resize the panels if necessary to fit the detergent boxes that come with this trick, then print out on high quality thick paper , glue the print-outs on to the prop detergent boxes, so you have a more realistic appearing box. Traditionally with "Soft Soap" you can do a real showy thing where you casually rip open the cardboard detergent box to show it empty , but to economize you can make the box re-usable with a few careful cuts with an Exacto knife and attaching small velcro tabs, so you can flip open the box to show it empty , but it can be re-used for several performances.