I have the Improvise pour France Musique set, and I like it -- though I do like his trio and duo work best.
I agree with Tom; I think "witty" is an excellent description of his playing. And extremely inventive. Solal definitely comes across to me as unique -- not "cerebral" (in the pejorative sense) or and certainly not soul-less, but definitely different. And that's one of the things that I like about him.
I like Richie Beirach too -- and people sometimes accuse him of being excessive refined or "cerebral" but I don't hear that either.
But, like I said, we all hear things differently!