I haven't seen it, so I have no opinion either 
way.  But it's one of the titles discussed in 
Susan Napier's _Anime: from Akira to Princess 
Mononoke_.  Like all good scholarly works, there 
are places where you think "god, that's really 
stretching it!"  but she does make Legend of the 
Overfiend sound more interesting than a mere 
excuse for tentacle sex.  I believe she describes 
it as an "apocalyptic" anime.  Like I said, I 
have not seen the beast; just wanted to point out 
that other viewpoints exist.

I agree 100% with your 2nd paragraph. OTOH it's 
at least as annoying to have people think "anime? 
you mean you actually watch Pokemon?"