Use Business Rule Engine to implement business logic that is modular, reusable and simple. It will allow you to operate on information contained in .NET objects, database tables and XML Documents. BRE also enables developers to create and maintain applications with minimal effort.
The Business Rule Engine can be a good way of to modularize the constantly changing business logic that is often developed inside Orchestrations, making changes a more smooth process since updating a policy to the latest version doesn’t require any downtime at all. With some training even non BizTalk developers or tech savvy non developers can create and test rules.
Business Rule Engine is also a high performance engine to evaluate business rules even when compared with WF Rules, read more on this topic WF Rules and MS BRE – Comparing Performance