The last release of JFBConnect for Joomla 1.5 was over a year and a half ago. It's held up extremely well with changes in Facebook. However, the latest change to the Graph API v2 will not work with JFBConnect v4.3.x for Joomla 1.5. For all Facebook applications created before May 1st, 2014, JFBConnect v4.3.4 should continue to work through April 2015. Apps created after May 1st will not work with JFBC v4.3.4 for authentication. Other features, such as social widgets should work as normal.
For a full rundown of the Graph API v2 changes, please see our
Facebook Graph v2 and Joomla
blog post.
I hope that helps explain. In general, I'd highly recommend looking into moving to Joomla 2.5 or 3.x which we'll be supporting for quite a few more years, at the least.
Thanks,
Alex