I've been using IBM's Jazz Team Server 1.0.1 recently. Most of my time has been setting it up for a new project where the client wants to use the Work Item Functionality to log incidents. We're using the Scrum process configuration and the default Work Items which come with this did not meet their requirements - not that is without us ending up removing functionality from the "Task" and "Bug" Work Items which we wanted to also use internally for development.
NOTE: IBM are aware of this pecadillo and in release 2.0 they will display the Name and the ID in the drop downs. Cool.