He wouldn't have any media. And nothing else, I think… Oh, contacts. He'll have your contacts, if he had that ticked. Possibly your calendars, as well.
Media doesn't transfer that way, and everything else that does is tied to your account, not his, so he can't use apps that copied over, for example.
If this is bothersome to you, better check that he doesn't have any information you don't want transferred.
iTunes will backup everything on the iPhone, including music, photos, SMS messages and contacts. In iTunes, with the iPhone selected on the left, click the Info tab and make sure data syncing is enabled.