There are many things that work well in the WaterSluice methodology. The WaterSluice methodology recognizes that people make mistakes and no decision can be absolute. The teams are not locked into a requirement or an architecture decision that turns out to be wrong or no longer appropriate. The methodology forces explicit freeze dates. This allows for the product to be built and shipped. It forces accountability by having decision points where, for the most part, things need to be completed. The first stage is iterative allowing for the correction of mistakes. Even after a portion of the system goes under change-order control, a decision can be changed if it is absolutely necessary.
The WaterSluice methodology forces the teams to think but does not require the teams to be clairvoyant. Sufficient time is allowed for the first stage to establish the confidence level needed for success. Communication is emphasized.
The WaterSluice methodology allows for fast interaction, up front, between all phases of analysis, design, implementation, and testing. This feeds critical information between all four phases. The implementation team doesn't waste time working on throw-away code because requirements are validated early in the process for feasibility of implementation.
The WaterSluice methodology can respond to market changes more quickly due to the iterative nature in each stage allowing requirements to enter and exit at each stage. The WaterSluice methodology tries to move all mistakes to the beginning of the process, where a restart is not very costly.