To the OP:
If you want a full-fledged Android experience or are a heavy gamer, don't get the KFHD. You're going to be disappointed. It's too locked down. It's not Android.
That being said, I love my Fire HD 8.9" tablet. Much better than my Galaxy Tab 10.1.
It does exactly what I want it to do- watch videos, read books, listen to music, and surf the web. The software is a bit buggy and at times it can be annoying, but it's still way better than any Android tablet for me. My view is different- I have a galaxy S3. IMO, why would I want to drop $300 device that gives me THE EXACT SAME EXPERIENCE that my S3 offers. OK, the "pure" android tablet will have a bigger screen. And it's likely going to be wi-fi only. It got old after awhile. I got bored with my iPad when I had my iPhone and got bored with the Galaxy Tab 10.1 with my S3. The Kindle is a different experience which doesn't make me feel like I'm paying for the same Android experience. The ads are not annoying to me- really, it's the lock screen ad that is glaringly obvious. There are ads underneath each item in the carousel that point out "customers who bought this also bought..." I've found some good books that way, so I don't have a problem with it.
I'd argue that you can still enjoy the Fire HD without Prime. But it depends.
- You can sideload YouTube and install Netflix for videos
- For magazines, you can download individual apps, i.e. GQ, Wired, etc.
- You can buy individual books from Kindle.
- In theory you can sideload zinio, nook, etc- not sure if these apps work.