Don't be under any illusions. Any online/cloud system you tie into with a mobile device, Apple, Microsoft, Google, Amazon, etc, has the capability of doing anything they like with your data. And all of them have been known to violate this trust from time to time. Whether on purpose or accidentally is open to debate. What ever you put "in the cloud", make sure it's not anything you want to be kept private.
That said, I have a 9" Fire HDX that I won at a trade seminar. It has a beautiful screen. I use it for watching TV on the Time Warner app when I use my treadmill. It has a lot of capabilities. But in a fashion like the older Barnes and Noble Nook HD (which I also have) it's also very locked down to Amazon only content. You can side load apps but you don't have access to the Google Play store, only Amazon's store. Save your money for a better tablet.
My wife has a Nook branded Samsung Galaxy Tab 4. It's a full blown tablet and it a far better tablet than either the Kindle HDX or the older Nook HD. It has the same interface and features that the Samsung Galaxy phones have. That one is my next tablet. Every so often it goes on sale for $150 which makes it the best table bargain on the market.