Ahead of today's Amazon Fire Phone reveal, the Seattle company teased press conference attendees a few days in advance by shipping them a copy of Mr. Pine's Purple House, a children's book that CEO Jeff Bezos declared his "favorite." The gesture came with a note implying that Amazon's next product, like Mr. Pine's house, would be "a little different" from everyone else's. The Amazon Fire Phone is certainly that—though not purple, nor particularly thin, nor ramped up with a crazy processor, nor even smothered in an airbag (the latter of which Amazon has a patent for, if you're wondering).

Heads up

As expected, the phone's biggest "unique" feature was its Dynamic Perspective system, which uses four infrared-loaded cameras to keep track of a user's head and adjust on-screen elements accordingly. After the reveal, we followed Amazon to its Seattle headquarters to see just how well this years-in-the-making tracking system worked in near-final hardware. More importantly, we wanted to learn how the company's heavily modified version of Android, FireOS 3.5, might fit into our smartphone lives. (See our hands-on gallery , as well.)

The first Dynamic Perspective test came from the animated lock screens, three of which we tried out: a forest, a hot-air balloon scene, and an active volcano. These all reacted the same as in Bezos' live-tests. Essentially, each lock screen contained animated, 3D scenery, almost like a small snowglobe, and they all moved sharply with twists of our wrists while moving ever-so-slightly with nods or turns of our heads.

These lock screen settings had limited range, so once we turned an Amazon Fire Phone too far to the left or right of our vision, the visuals would freeze in place. Impressively, they'd remain frozen in that range until we turned the phone to the point we'd been at before, seemingly within only one or two degrees, and then they became living snowglobes again. That seemed to prove out Amazon's claims that the Fire Phone could maintain perfect readings of x, y, and z axes.

We test the Amazon Fire Phone's head-tracking capabilities with a demo that doesn't care much for cameras in the way.

Once that party trick lost its luster, we only found a few particularly useful applications of Dynamic Perspective to apps. The most obvious was in Maps, which brought up tooltips on the map screen whenever we slightly tilted the screen (known as "peeking"), complete with business names and star ratings. Book and website reading let us tilt the phone up and down to browse as well, though we covered our faces with a camera while testing these and found that the functionality still worked. This made us wonder if that implementation is nothing more than gyroscope readings.

Otherwise, we didn't see transformative uses for head-tracked phone movements. In particular, the Amazon shopping app, which let us tilt the phone to flip through dress designs, felt a little too sensitive for our liking. The games we tested, Threes and Stagedive Legends, had absolutely terrible head-tracking implementations, quite frankly; the lag between motion and on-screen action was too unbearable, a la Kinect.

We had a representative at our side throughout the demo, and any time he had control of a head-tilting moment and aimed the phone my way, the control or sense would become wonky. This noticeably occurred at least six times in our half-hour of testing. "It's seeing both of our faces," he'd say apologetically each time. That's a huge hurdle to overcome, especially if Amazon expects to virally advertise this phone by having enthusiasts show it off.

It's not in the wrist

The Amazon Fire Phone doesn't have any Android buttons on its front beyond the home button. Instead, users are expected to jerk their wrists leftward or rightward to bring up app-sensitive menus. Between this and head-tracking, Amazon seems to believe it can deliver a true one-handed phone experience.

In our brief demo, this wrist-jerking began to hurt very, very quickly, and when we said so, we were reminded that each app could have those menus brought up by swiping from the right-most or left-most edge of the screen. (Additionally, "back" is triggered by swiping from the bottom.) That introduced a whole new batch of problems, especially when dragging around a map screen to look for a coffee shop. It didn't take long to accidentally bring up the right-most "recent searches" menu or left-most "preferences" menu (though thankfully, the swipe-from-bottom seemed to have a better dead zone).

We move the Amazon Fire Phone around to show off its lock screen animations.

We were happy to see that Amazon's internal maps app included robust Yelp integration and transit support, but we didn't get answers as to how many cities it supported for bus/train routing. We did get an answer about Google Play integration, however: "We don't have Google services on the device, no," Software Vice President Rob Williams said. Thus, don't plan on installing the likes of Google Maps, Hangouts, or even Snapchat (which requires Google Play for Android installs).

Williams confirmed that FireOS 3.5 is running on the Android 4.2.2 (Jellybean) base, and that Amazon is working to bring FireOS in line with Android 4.4 as soon as possible. This, in particular, will solve the phone's current lack of support for low-powered Bluetooth devices like Fitbits. However, when asked directly about what timetables users should expect for OS updates, Williams dodged the question by instead clarifying the differences between FireOS and Android. He added, "your readers know that difference. They are very sophisticated." (Sophisticated enough to know when a question has been dodged, we should add.)

Bring back Firefly

Rounding out our demo time, we took an Amazon Fire Phone to a wall covered in posters and Amazon products, then loaded the Firefly app to see how quickly the phone could recognize everything. Our results weren't quite as snappy as Bezos' presentation would lead you to believe. In particular, Firefly kept re-identifying a single book in the corner of the image, ignoring another book in our screen's dead-central zone even if we tapped the screen to focus.

For the most part, however, Firefly took an average of 1.5 seconds to identify and load context-sensitive choices for a product—iHeart Radio options for overheard songs, shopping choices for books, nutrition information for food, and so on. It was also surprisingly fast at culling URLs and phone numbers off text-loaded posters, though we can't imagine a moment in which either taking a photo or copying the pertinent info into a keyboard wouldn't be a preferred method of grabbing such details.

We use the Amazon Fire Phone's Web browser to see what's happening on Ars Technica today.

Speaking of cameras, we couldn't test the Fire Phone's 13MP camera very intensely, especially in an office room full of shut windows, but we snapped photos of our own laptop and found that the advertised ability to compensate for hand shake didn't really show through. Pinch-zooming on our photos showed significant blur on photo details, particularly the letters on our keyboard. We'll test the heck out of this with review hardware, but we didn't walk away impressed.

In fact, our general takeaway was one of shrugging our shoulders and remarking on the Android features we missed. The "home" screen is a giant mess of icons, and it can't be improved with custom widgets. According to representatives, the default Swype keyboard can't be replaced with a third-party option. The lack of dedicated Google apps on a mostly Android device, especially the oft-improving Google Maps, bummed us out.

Whether the phone's unique features, particularly head tracking and comprehensive Firefly searching, prove disruptive enough to win doubters over remains to be seen. Amazon has promised that review hardware will land in our hands "by next week," at which point we'll set an Ars staffer on Fire and see what happens.