Amazon's upcoming smartphone to feature 3D interface

Amazon Kindle Fire rear
Reports of an Amazon-made smartphone have been rumbling through the rumor mill for well over a year now, and tonight another leak has surfaced with purported details on the retailer's handset plans. According to sources speaking to TechCrunch and a post on HackerNews, Amazon is actually cooking up a pair of smartphones, with one high-end model that features a 3D user interface and a second, cheaper unit.
The higher-end of the two is reportedly codenamed "Smith" and is said to feature four cameras on the corners of its face that will track a users head and eye movements. The phone will then move its user interface around to give the illusion that it's in 3D. This would allow users to see buttons move around and possibly even "peek" off the edges of the screen. The software that's being worked on would allegedly recognize the face of the device's owner and ignore others in order to ensure that it's displaying its 3D interface correctly.
Amazon is also rumored to be considering another feature for its high-end Smith phone that would allow the user to snap a photo of an object in the real world using a fifth camera on the device's rear, then find the corresponding product on Amazon for purchase. It's said that this feature could be used to help offset the cost of the phone itself. There's no mention of how much that cost could be, but it is said that the Smith isn't expected to launch this year.
The second, low-cost phone is described as a "cheap" model that would run the Fire OS similar to what's used on Amazon's Kindle Fire tablets. None of the 3D features found on the Smith would be present, which isn't a surprise given that this is supposed to be the more affordable model. Most of the other details on the low-cost phone are still up in the air, but it is said that staffing for the device has been shifting around quite a bit and could cause the phone's launch to be scheduled for next year.
These two devices are still very much unofficial at this point, and it's possible that one or both of them will never even make it to market. Considering Amazon's growing line of Kindle Fire hardware and the continued consumer adoption of the smartphone, though, I wouldn't be surprised if Amazon were interested in trying to break into the wireless market. This Smith phone and its 3D interface sounds pretty nifty, although it's unclear how cool or useful it'd be in day-to-day life. Still, the phone could at least be used as a jumping off point to help Amazon develop other phones that it does launch.
What do you make of these Amazon phone rumors? Would you use a device with a 3D interface like the one described on the Smith?