I am disappointed. Clearly Amazon is not sure it will be able to derive enough additional revenue from the phone to sell it at a more subsidized price. Something that they are arguably doing with the Fire tablets. Throwing Prime in for a year is a gimmick to make the phone seem less expensive.
Google Nexus phones are still my benchmark for good hardware at a reasonable price. Sadly with Android Silver maybe that's going away too. I am now pretty comfortable the Fire smartphone will not devalue my collection of Nexus 4 and Nexus 5 phones (starting a side hobby activity of buying broken Nexus 4 and 5's and fixing them up for resale at a profit). Fire smartphone not having SD card slot or removable battery also helps with this.
The four cameras for 3D perspective is innovative, but doesn't add that much to the cost. I also think the feature is going to be common soon - as in there are other products being developed with this feature, not as someone copying Amazon starting today. I do like the tilting feature showing additional information. Of course, we will need Google apps catch up with this new hardware feature to take full advantage of it. This certainly looks to be an easier phone to use one-handed - valuable feature as I have a baby and a toddler
At $649 without contract, I think it costs too much and will likely pass. There is no way I am signing an AT&T contract. I use literally 10 minutes of airtime a month and a fair amount of data (and Google Voice for texts), and feel being forced to pay for unlimited talk/text just to buy data is unfair.