Great till he kicked smack, uneven but sometimes good till he kicked booze.
That's in terms of his studio output, he probably put on good live shows most of the time until pretty late in his career. Also I like From the Cradle which he made after being clean for over a decade. And the very next album after that was Pilgrim. The last studio album of his I remember drawing any attention at all was Me and Mr. Johnson in 2004. That seems like the kind of album I'd end up defending while everyone else ragged on it but I actually thought that it sucked and was boring.
He put out an Christmas album this last October, which I only learned just now from looking at his Wikipedia page.