Certainly true, and most of them have been borderline-unusable crap. But I wouldn't lump the Kindle Fire in with those. The Fire has a specific set of functions, and an interface optimized for them; it's more limited than the iPad (or the Galaxy Tab or Motorola Xoom or other general-purpose tablets), and both its price tag and its marketing reflect that. By all accounts, like the e-ink based Kindles before it, it focuses on its limited number of functions and does those very well.
A lot of analysis focuses solely on market share and thus misses the point. I don't think the Kindle Fire will take many sales away from the iPad; what they will do is expand the tablet market as a whole, bringing in folks who have $200 but not $500 worth of movie-watching and Web-surfing they want to do (my solution was a $300 used iPad). Apple will continue to have a smaller slice of a rapidly-growing pile, and for at least a couple more years will continue to sell as many iPads as they can make.
Fire may do it’s thing better than like-priced competitors, but people will still be expecting grater capability at an impulse price.