It is true that you use it without their proprietary client (via SMS). But much like the Slack IRC bridge, don't expect it to stay up forever. It's also not feature complete by any means, and still sweeps up your data. Plus, it's owned by Microsoft, and let's not forget EEE...
Remember when Google Hangouts removed XMPP support?
Just like that.
@polaris yep - be very very wary. In fact, ignore it.
Pretty cool place for libre software loving nerds to hang out.