I don't really mind his playing, in fact I think he's a pretty good guitarist... for what he does. If they would have played a bluesy Dead-related jam like What Sin it probably would have been great. There are a number of other Cardinals song that I think him and his band could have done a pretty good job with, but for some reason Come Pick Me Up just didn't work for me.
Not really fond of Mayer harmony vocals. He's no Neal Casal.