Meaningful differentiation, speedy performance and fast-moving updates.

Every Android phone maker has a different approach to software. Some, like Samsung, go all out with a highly customized interface that touches every corner of the way Android looks and works. Others, like Motorola, stay true to the visual style of "vanilla" Android. Then, somewhere in between, you've got companies like Sony.

Sony Marshmallow launcher

In recent years, Sony has gradually cut back on visual cruft, to the point where its current crop of phones, the Xperia Z5 series, look and behave a lot like Google's vision of Android.

So what's next? Well, alongside its official firmware updates for Xperia phones, the firm last year opened up a "Concept" software program for fans. The big idea is to rework Sony's software from the ground up, using vanilla Android as a base and layering on Sony features as needed. Following the success of the original Lollipop Concept over the summer, Sony rounded out the year by bringing Marshmallow Concept software to a select group of Xperia Z3 and Z3 Compact owners.

It's a step closer to Motorola's way of doing things. But the Concept firmware is about more than just vanilla Android. The program involves Xperia owners in Sony's software development, using surveys and a Google+ community for further feedback and bug tracking. Effectively, it's a fast-moving yet surprisingly stable software track for power users. And it's pretty slick.

Sony Concept

A fast-moving yet surprisingly-stable software track for power users

Sony's Concept firmware runs on the Xperia Z3 and Z3 Compact, which are a couple of generations removed from Sony's latest stuff. Then again, they're based on the still-great Snapdragon 801, arguably a more stable development platform than the newer 810.

It's a common misconception that it's UI stuff that slows Android phones down, and if only manufacturers would leave the OS as Google intended, all would be well. But stock Android doesn't guarantee speedy performance, as anyone who's used a Moto X Play will know. Code still needs to be optimized, and stutters smoothed out, and that's exactly what Sony has achieved with its Concept firmware. (Of course it also helps that they're starting from scratch with minimal bloat.)

The result? Probably the fastest Android phone I've used, and that includes 2015 models like the Nexus 6P and Samsung Galaxy S6 edge+. This software absolutely flies, putting to shame the vast majority of newer and more expensive handsets.

The Xperia Z3 on the Marshmallow Concept firmware is probably the fastest Android phone I've used.

The Marshmallow Concept's performance is about more than app load times and animation fluidity, though. The Z3's battery life — already pretty good even back on KitKat — gets a welcome boost thanks to Android 6.0's "Doze" feature. You'll miss out (for now, at least) on Sony's Stamina mode, which lets you cut down on background activity to save juice. However Marshmallow's built-in power-saving features mostly make up for this.

Much of the Concept firmware looks and feels like vanilla Android. The phone dialer and contacts app are faithful recreations of Google's stuff. And the same goes for core UI stuff like on-screen keys, the lock screen and the notification shade. There's been some icon swappage in the Settings app, but the way this works is largely unchanged.

Sony Concept

Sony's Concept doesn't come with the Google Now Launcher — though you can download this separately, and it's right at home on a device running this firmware. Instead there's the latest version of Sony's extremely lightweight home screen experience. Sony's new launcher looks and feels a lot like Google's, but with some subtle visual changes. Dig deeper, though, and you'll find a host of customization options, including theme pack support, transition effects and the ability to switch to an iPhone-style grid of all icons instead of the traditional Android app drawer.

Aside from the launcher, Sony has only sparingly added its own software. Out-of-the-box additions include Album, the Sony gallery app with PlayMemories support, as well as Z3's familiar Camera app, complete with AR effects (for that picture that's just not complete without a virtual T-rex). Sony's also got its own email client and Music app (don't call it "Walkman"), as well as an app for managing UI themes.

Sony apps

And that's really about it. Everything that's there is meaningful differentiation. The disappointing "small apps" that used to live in the task switcher (and which I never used anyway) are gone. The Sony Messaging app has been retired too, it seems. Nowhere has Sony seen fit to reinvent the wheel, and that's great.

Nowhere has Sony seen fit to reinvent the wheel, and that's great.

As well as the official Google+ group for the Marshmallow Concept, Sony has been taking feedback from Concept participants through its built-in Beta Feedback app. Surveys land periodically, quizzing users about which features they miss from the official Sony firmware, and how often they'd like to receive software updates. It's also a handy place to report the few bugs that have inevitably cropped up in such a fast-moving software project.

The pace of over-the-air updates has been quick so far. Concept devices got the Android 6.0.1 update just a couple of weeks after Nexus phones, though we're still waiting on the January security update. Some hiccups have emerged along the way, but for the most part I've been impressed with the stability and usability of this little software side-project.

The direction Sony's heading in with the Marshmallow Concept is where we'd like to see Android in 2016. Not everything needs to be bone stock Android — but if you're going to differentiate, do so meaningfully and not just for the sake of being different.

There's no guarantee that anything like this Marshmallow Concept will ship on the Xperia Z6 series or whatever's next from Sony when it arrives. But as the Concept project continues, it'll be interesting to see how much of this fresh approach to software feeds into the coming generation of Xperia phones. As for the Concept program itself, it's not going anywhere — in fact, Sony is in the process of expanding it. And even as new phones arrive, it should remain a place for the most enthusiastic Xperia owners to have their say, and stay on the cutting edge of Sony's software endeavors.