This analysis makes sense, and states anything that avoids code duplication and simplifies maintenance speaks for a service layer.

What is the technical behavior?

1. When a service client references a service, does it do so at runtime, or does it happen at compile time?
2. When I change something in the service layer code, will this change be automatically taken into account in all it's clients, or do they need to be individually recompiled?
3. How does this make sense from a testing point of view - I have working code, based on some code from a service, but if that service changes, my code might break?!