I have seen BO, and received a little bit of training in it. From what I have seen BO is very powerful, but the user interface is a bit hard to use. CR 2008 has a good user interface but not as powerful.
Probably the biggest stumbing block will be to learn the differences on how to create groups (and their limitations), parameters and formulas. Of course I come here almost every day to learn more about CR and I have been creating CR reports for years.