Was involved with a Biz Object project a couple years ago.
On the whole it's a waste of time and a ball-ache to integrate into. We ended up implemeting the majority of the reporting functionality in session EJB's and at the same time gave the punters precisely what they wanted and identified use cases that had not previously been considered.
Like anything else in IT, when another component is introduced to a system the likely case is that problems arise.