Prechter is an interesting guy, imo, but often too ham-handed and doctrinaire in his studies. So probably neutral. That would, of course, explain why he's been wrong a lot over the last 25 years. But very right over the past couple.
I personally believe any person who wishes to invest in the capital markets must have at least a basic understanding of Elliott Wave theory. And he is really the king of that - the developments he made there are probably his greatest contribution.
Over the last 6-12 months or so, I've really been refining my (previously lax) study in technical analysis, including Elliott Wave, and have been using it (to my improvement) in analyzing any number of things long-term, whether market-related, or more apropos to this site, polling. It has helped
a lot in the latter - can almost see the trends before they develop.
Anyway, he is definitely one of those people more bearish than me long-term on the state of things (though I don't deny his prediction could happen). Though I can understand why - pretty much all of the technical analysis I do (in addition to the economic fundamentals) still says there is, at minimum, another wave down.
I'm not surprised Gully refers to him as a pseudoscientist. Plenty of people call technical analysis a pseudoscience of sorts anyway.