Having been a MS Project user for many years, I find that trying to switch to OWB is a royal pain. What bothers me the most is the difficulty to enter projects into OWB right "out of the box". I find it very confusing to understand the different methods of separating task levels in OWB. In MS Project, this was a non-issue. Subtasks could easily be added by indenting them to the appropriate level. I had the time & space here to discuss the ful list of issues I've had, but at this point, I can't afford to switch from MS-Project to OWB. :/
Your difficulties might be because of the view you were using. If you have the task type in the view then changing the WBS is a single key stroke. A pre-defined view for this called WBS definition can be found on the Planning section of the Left Nav bar.