I believe he's largely held in contempt, either ignored or dismissed as a loon. Unfortunately, Alexander has done a few things to paint himself into this corner. He seems to have a need to be regarded as a world-historical genius, which isolated him and turned his work into something a bit cultish. That's a great pity because his core ideas are so vital.
That's correct, in the USA, at least -- although they seem to think better of him in Germany (at least, they did a decade ago). He did pioneering work on using computers for design at MIT in the sixties -- but it never really took off, or even worked terribly well. "Pattern Language" is seen as naive and ridiculous in the "top" schools -- but I agree with gruseom that there's a lot of wisdom there. We'll come back to it, as the cycles make their slow turn away from mannerism.