The Amazon T&Cs might put you off - have a good read before you even think about it.
I suspect (but have zero evidence)that Kindle buyers are not likely to be app purchasers and while Android users generally can use the Amazon store I am not at all sure this is their first choice when looking for an app.
It might be that the latest Kindle models will enter the mainstream as Android tablets - have to see if that happens - the hardware specs are good. [anyone know if they now ship with an up-to-date Android version?]
You would think that the amazon store would be very good at offering apps alongside books if they might have a similar appeal (say a navigation app alongside books on similar subjects) but I have seen little evidence of such cross marketing - if that started to work then it would be a strong indicator that the Amazon app store was capable of making an impact.