We first evaluated Mule and really liked it...this was on version 2.6.1.
However, management decided they wanted a complete JBoss stack, so we used the JBoss ESB.
After porting everything over that we did on Mule to JBoss ESB (no small task), we had a few observations:
* Mule had more mature API's and much more documentation/examples.
* Mule was less intrusive and easier to use.
* Running the JBoss ESB and Portal server on the same JBoss A/S is possible, but very tricky. For example, we have not been able to update to the latest version of Portal because ESB requires a different version of the A/S
Thanks a lot Swist for sharing your experience.