I think people hate this movie more for what it *isn't* than for what it is. It came out during a Kaiju Drought when we were hopeful for anything, and pining for films like the Gamera trilogy and the Millenium films. What we got was a super goofy, staight-to-video quality, production that doesn't take kaiju or sentai genres seriously, and doesn't really take itself seriously either.
Death Kappa is fine for me, right up my alley. Totally one of those "WTF?!" Japanese movie experiences. Throw in that villain from World War II--their equivalent of a crazy Nazi scientist--and a kaiju battle at the end, and I'm sold. All the rest of it is just part of the crazy experience, I mean, it may not work as a kaiju genre satire, but the elements of J-Pop satire are actually pretty funny/disturbing.
As a weird Japanese movie, it works
"...WILL. IT. WORK?"