[Elias]

For normal site-users it can be nice, that they’re logged in at WordPress if the’re registered and logged in at bbPress. The WP comment form is simpler for the logged-in-users, they don’t have to type their name, mail adress and homepage. If you configure your WordPress in a way which requires registration of commenters, there is an additional benefit for administration. There are always some hand-registered SEO-spammers, and it makes you less work if you have only one user database. The mapping of WP user roles to user roles in bbPress may save some work too.

For most installations, the integration isn’t needed. Always remember that the bbPress installation with integration is significantly more complicated than a normal bbPress installation and may lead you to incompatibility issues with future WP releases. Think about it before doing. I love it, but it is a little hard sometimes…