I also like the way we can debug a service. On contrast to the Analyzer where you actually record the service execution at runtime and examine the trace, you can directly set a breakpoint on an action within the model. With the Interactive Debugger you can step through the model at runtime and check all execution paths and object values. This works even for asynchronous activities like in persistent state machines.
See also in the FAQ: How does debugging work with the E2E Bridge?