Yes, it’s now free. But keep in mind some key things remain broken in Corona.
Facebook sharing on Android via the social plugin is broken. Corona is fixing that, but no release date has been confirmed. See: http://forums.coronalabs.com/topic/52755-can-corona-enable-limited-facebook-sharing-on-android-via-nativeshowpopup/
Instagram sharing on iOS is broken. Corona has specifically declined to fix this, even though an Enterprise developer has published a plugin that does work with Instagram. See: http://forums.coronalabs.com/topic/53371-supporting-ios-modal-share-action-sheet-airdrop-print-add-to-home-screen-add-bookmark-add-to-reading-list-etc/
There were sharing problems on iPads that caused the app to crash, but I think this was fixed; I can’t remember. You should check the forum archives on that point.