You'd really prefer to be running on the app server directly to take full advantage of all its capabilities. So, I'd rather be running on JBoss or even Glassfish than on embedded JBoss in Weblogic. When that isn't an option, then I'd be very comfortable running embedded JBoss. I've only run embedded JBoss in Tomcat, but when I do I'm barely aware that it is there.
Believe me, it it were up to me, I would love to run my app on JBoss. Unfortunately, the platform of choice for my client is WebLogic--and old-school WebLogic at that. So I have no recourse.
Given that constraint though, I have to admit it is really cool that I can deploy an EJB3 app to WebLogic without any worries.
Does anyone else have any experiences or tips they care to share?