And in fact, it's not just your info -- you can punch anyone's gamertag in and instantly see how far they've gotten in game. Is your friend bragging that he finally beat it on Legendary? Dial him up and check out that claim with ease.
Very impressive, and to tell the truth, I'd like to see more tools like this (maybe even some official ones?) to extend the various games we play. Considering how tracked and connected videogames can be nowadays, it's exciting to see possibilities like this arising.