Flexibility and high performance.
I can perform integrations with any environment and
scenery as well as growth in apps integration, is an agnostic tool architecture
ie can generate components on different architectures are JEE or .Net.
Mule ESB has a lot components and tools that apply integration patterns making it easier to development without much knowledge of patterns
The Spring components are easily integrable in Spring, JEE , any Java applications and any application regardless if they are web or standalone