I use my Fire at least 2 hours a day (at home and the gym) for reading and surfing. However, it has two major defects.
1) Amazon appstore only (I haven't bothered rooting it).
2) Wonky interface. It's android and you can tell. It's like using a cheap android phone, unpleasant and slow. (I have a droid bionic that is much faster, but obviously more expensive).
At this price point I can easily buy another $200 table and not feel bad about it. Plus I still get the kindle app, my amazon apps will all move over.
I use my Fire way too much not to upgrade to something better. I do this for the 7" form factor, the 10" tablet (android or iOS) simply would not be as useful.