I would have thought the trilogy of Legend, Anniversary, and Underworld would have been made backwards compatible back when the announcement of Rise of the Tomb Raider being Xbox exclusive hit, but alas no. We finally get to play Underworld though! The Xbox exclusive DLC is backwards compatible as well! Hopefully the others will follow suite soon.
Crystal Dynamics have also given us an extra treat! Check out these unreleased box art explorations for the game! They are pretty cool if you ask me.