Not that bad
I've pulled several of these disposals after seven years of use. Seven years for a disposal is a very decent lifespan in this century. (All were in a large rental housing complex, in case anyone here is wondering about the timing). As to the whole 'plastique' stuff, I've never seen that be the cause of failure, yet.
No, they aren't as well built as the top of the line stuff being put out by Emerson, but they're not bad.