The material mostly (all?) new and drawn from the upcoming album Blues and Ballads. The morning of the concert---which happened to be the final one in their tour---he retweeted a bit from this review in the Boston Globe
[Brad Mehldau] flashed facets of his renowned pianism: crystalline touch, deep lyricism, harmonic sophistication, adroit use of space, and the otherworldly independence of his right and left hands.
I cannot really describe his style any better than this. If you get a chance to see him, go!