It's and entire album of collaborations, mostly duet vocals, and he's done them with a varied assortment of outstanding singers.
The result is a near perfect disc of amazing songs, where despite a cohesive feel due to Shear's writing and voice throughout, almost sounds like a mix due to all of the amazing vocal contributions.
Highlights for me are "Sealed Up Hollow" (Margo Timmins), "Let's Go Slow" (Rob Shear) and the Rosanne Cash duet "Who's Dreaming Who", as well as the incredible "Restaurant Scene" with Susan Cowsill and "Windows and Walls" with Patty Griffin.