BuddyPress.org

All wire messages and BP 1.1 status updates will be converted into BP 1.2 activity items.

Users and groups will remain as-is.

The only thing is if you’re dependent on BP 1.1.3 plugins, most of them won’t work off the bat until plugin developers have a chance to modify their code to 1.2 standards.

Also, if you’re using a highly-customized BP theme, you’ll have to adjust that as well.