Various possibilities, eh?

http://en.wikipedia.org/wiki/Konnyaku gives
In Japanese cuisine, konnyaku appears in dishes such as oden. It is typically mottled grey and firmer in consistency than most gelatins. It has very little taste; the common variety tastes vaguely like seaweed. It is valued more for its texture than flavor.

http://asiafood.org/glossary_1.cfm?alpha=D&wordid=2545&start... gives
Konnyaku is used primarily as a texture ingredient, with not much flavour but a uniquely chewy, gelatinous texture.

If something more concise is called for, then perhaps a shorter version of the above:
"firm yet chewy"
"chewy, gelatinous texture"
etc.

Now I'm craving for some 筑前煮 :-(