When I saw the prototype YotaPhone last year at CES 2013, I was legitimately impressed with the concept - a smartphone with a standard, full-color display on the front, and a black and white e-ink panel on the back. The applications, functional and aesthetic alike, were not difficult to see.

But the original YotaPhone was quite hefty, both displays were a bit small at 4.3", and the e-Ink panel wasn't actually touch-enabled, but rather was controlled by a capacitive touch panel along the bottom of the device. And, honestly, it wasn't exactly what I'd call pretty - it looked like an engineering prototype, not a piece of consumer hardware.

The new YotaPhone addresses all of these concerns, and is the more mature product I think many would expect of a modern smartphone producer. The new YotaPhone no longer relies on a capacitive touch strip to control the e-Ink display, as the now 4.7" panel is fully touch-enabled. The full-color AMOLED display has grown to 5", and the device is powered by a quad-core Snapdragon 800 processor. Android 4.4 is there, too, and hopefully an even more recent version will be available when the phone launches.

Which brings me to what is probably the single biggest problem with the new YotaPhone - it doesn't come out until Q4 of this year, and then not in the US or Asia for a few months after that, meaning 2015. By that time, the new YotaPhone will be quite the old YotaPhone, and I doubt anyone's really going to care all that much about it at that point.

Still, Yota's innovation with the e-Ink panel is something worth paying attention to, if only to inspire others to pursue the concept. I doubt we'll be seeing Yota make a big splash in term of sales once the new YotaPhone finally does go on sale, if only because of the brand's relative obscurity outside of its home market of Russia.

So, what's new with the new YotaPhone's software? The new device obviously takes advantage of this enhanced touch-enabled e-Ink panel in a few ways. First, the rear panel now serves as a notification hub - you can see missed calls, SMSs, and emails on it, which is definitely pretty convenient. You can even make phone calls using only the rear panel, though this functionality wasn't demonstrated to us. Yota's built-in reader app allows you to open up an eBook and then send it to the back of the device, where you can just swipe to advance pages. You can also, of course, change the background on the e-Ink panel to whatever you choose.

Interactive with the e-Ink panel using touch is also a bit unsettling - going from the extremely responsive AMOLED screen up front to the slow-to-refresh e-Ink display makes for a jarring transition. I often found myself pressing things twice or three times on the e-Ink side because I didn't believe the action had registered, and this lead to sometimes wonky results. Granted, the device we were using is a prototype - the new YotaPhone is a long ways off from mass production just yet.

All in all, the new YotaPhone is the evolution of a great idea, one that I think more smartphone manufacturers should be paying attention to. It's just a shame that only Yota has really pursued it.