I've been listening to the new 2-disc Sondheim Unplugged (volume 1).
42 songs from the entirety of SS's career, sung simply to piano accompaniment. The tracks have various degrees of success. The piano is closely miked, claustrophobic, and occasionally not entirely in tune. It's kind of an ugly sound.
I enjoyed some of the tracks, but as a whole the effort is very uneven. Too bad!