Only one data point, but I'm a Prime customer that spends significantly more than $1340 a year on Amazon and I have a Nexus 5 which costs just a little more than half what this Amazon phone costs.

I don't need a "budget" phone, I can afford something much higher-end; but I still like to get value for price and in the face of the Nexus 5, the Moto G, the Moto E or the Lumia 635 all of which cost half or even less than a quarter of the price of the the Amazon Fire phone, it just doesn't look like a good value to me.

YMMV if the 3D perspective thing is that appealing to you, or you want a cellphone with a relatively very good camera, but neither of these are particularly important to me.