You’re right that BP is a plugin, but we don’t really take over any of WordPress. We extend some parts of features found in WP — for example, user profiles — but we don’t take anything away. BP and other plugins work together fine.
Was there a particular concern you had?
If your concern is what happens to your WP install, then probably the important aspects you need to know are that activating BP doesn’t make any changes to WP other than it adds a series of new tables for it’s own use, as Paul says it then extends certain WP aspects such as profiles but that doesn’t mean it changes how WP works those aspects it simply adds more depth within it’s own tables.
I think your primary concern? is covered by : You can safely disable BP and revert your site to simply running WP without any issues, you may be left with a few legacy files such as the necessary ‘page’ files but those don’t impact things and could be removed if necessary.
