At least the stuff I've seen is more a criticism of the lack of functionality for the Rabbit, esspecially unique functionality or areas where it excels. The fact that it is basically all able to be contained in one app is viewed as evidence of the relative simplicity, and the fact that (as reviews highlighted) a phone provides a better interaction method compared to the dedicated devices just highlights how unnecessary the hardware is.
Basically, its competing against phones in functionality, but a phone at that price can do everything it can and better, plus so much more. Even worse when considering everyone also already owns a phone and won't be able to replace with a Rabbit.