The way I see it the book accomplishes exactly what it sets out to do-the Animorphs go back in time and have an adventure with dinosaurs. It puts our heroes into a real wilderness survival story and introduces whole new aliens.
Well yes, it does; and I'm all for "go back in time, dinosaur adventures." But in a very B-movie sort of way (which isn't to say that I am not capable of appreciating the entertaining aspects of a B-movie despite their flaws), where the time-travel didn't make any sense but it was just given to you and you have to just accept that it happened anyways. I think sci-fi literature has come a long ways in the last half-century due to reliance on high standards of scientific and engineering plausibility even when (perhaps especially when) the science is only theoretical. I almost said something along the lines of "this isn't fantasy," but even in a world ruled by magic, fantasy novels still make sure that the events in their universe take place according to the rules and methods that explain how magic functions within it.
Again, in general the adventure itself was good, but it is fairly poor literary form to tell the reader "It happened this way, don't worry that it doesn't make sense" when it really could have worked in a plausible way without effecting the plot at all; I really think it was entirely within KA's capabilities to have created it in a cohesive, reasonable manner.
