I was excited to get the chance to see this last night after missing it's earlier run, and I'm glad I did. It's certainly different from what I'm used to (more theatrical music than musical theatre), but I enjoyed it. ColorTheHours is right about feeling the music as much as you hear it; there was one moment where I could feel the sound vibrating through my body so thoroughly, it truly felt reminiscent of the religious experience Christian intended. It reminded me of what a unique and distinct pleasure it is to experience music live.
Having seen other things in this space at Signature, they definitely made it feel much more intimate than it has previously. The entrance to the space is in a different location than I was used to (to the left of the lobby bar, rather than to the right) and you have to travel along a path underneath all of the risers before entering for seating. The main playing space is only about the width of a subway car, I'd say, and the performers are regularly along the stairs and throughout the house. While I missed the Ars Nova run, I can't imagine it was much more intimate than what's being presented here.