Caroline,
I installed bug-tracker today, too and it went very well (except I had cloned some of bug-trackers workflow service contract implementations _as is_ for a package I'm working on, so that choked because it was a name clash).
My first experiences with the new workflow package has been very pleasant indeed. Lars docs are great, and it's pretty easy to make a package use workflow if you look at bug-tracker while developing it. Thanks Lars!
As of yet I have merely found one *tiny* thing to pick on, and it is that there is no tcl api for deleting a case (there is a plsql api, though.), which you must do before you can delete your associated object, otherwise you cannot drop your package cleanly.
I am sure you will enjoy developing with the new workflow, and I hope more and more people will start doing it!
/Ola