Purchased the fire phone for myself and my two kids. They instantly had access to the family collection of Amazon Music, including CD's that we had purchased decades ago that Amazon had transcoded to mp3 for free. They could tell me what they wanted me to get them by adding items on Amazon to their own dedicated wish lists. They had access to email, a generally good phone with decent display, networking functionality battery life, and camera. The only thing wrong with the phone was that it didn't connect to the Google App Store. No big deal..use 1 mobile market for any absolutely must have app that wasn't on the Amazon market place.
Our total cost for three phones was amazingly cheap, roughly $400, for which we received $300 in credits towards amazon prime subscriptions which we have paid every year since the service was first offered. No paying for the following 3 years.
The phone also notifies us when Amazon orders ship, when fedex packages arrive, and doesn't spam us with ads or treat all our information as their product -- Amazon is actually pretty decent with privacy on the phone, as opposed to Apple and Google. I honestly also have no interest in being a subscriber of the Google store or buying any media from Google. Amazon has a much better marketplace for songs, books, and videos...and it gives a great selection of free books, music, and movies with the prime service.
So, sure, if your young with no kids your responsible for and just trying to use the latest android features in the cheapest manner possible - get a google phone. For the rest of us, Amazon actually did a surprisingly good job with the fire.