I saw them perform at the Ravinia Music Fesival years back and had become fans of their with their Grammy-winning album, After the Ball, which was a collection of turn-of-the-century songs -- some famous, many lost today.
As I said, I love how they give a sense of the song in its time. But I also love that they, not surprisingly, include the verses to songs which -- even if the song remains known today -- are long forgotten. And that helps give a richness to this old songs, showing them as little stories, not just "ditties."
Here's an example. It's a song which, while not still-famous is nonetheless likely pretty well recognized, "I've Got Rings on My Fingers." But it's the very funny, odd verses that gives you a very different picture of the song than you no doubt ever had.