1、Loose coupling is a fundamental concept of SOA(and large distibuted systems in general) aimed to reducing dependencies between different systems.
2、There are different forms of loose coupling,and you will have to find the mixture of tight and loose coupling that's appropriate for your specific context and project.
3、Any form of loose coupling has drawbacks.For this reason, loose coupling should never be an end in itself.
4、The need to map data is usually a good property of large systems.