It's been promised for years, but now it looks like the first Ubuntu phone is actually happening. The Aquarius E4.5 Ubuntu Edition is expected go on sale in parts of Europe within the week.

Canonical, the company that leads the development of the open-source Ubuntu OS, will sell the Aquarius phone on BQ.com for just 169.90 euros, putting it in competition with low-to-midrange phones. Its specs are pretty decent for that range: It packs a 1.3GHz quad-core MediaTek processor, 1GB of RAM, 8GB of storage, an 8-megapixel rear camera and a full HD (1080p) resolution display.

Where Canonical hopes the phone stands out is in the Ubuntu mobile experience. The interface has a number of swipe-from-the-edge gestures: You swipe from the left side to call up a type of dock with all your app icons in a vertically scrolling line. Swiping from the top reveals quick settings and recent calls. Swiping from the right side lets you see all your open apps in a scrollable stack of screens.

You can also switch from app to app by swiping right of left from the middle of the screen, with each app sliding in on its own "card." Canonical calls this kind of card-based navigation Scopes, and it claims it's easy to adapt a web app to the system.

Individual elements get gestures, too. A contact on a list, for example, can be dismissed or acted upon depending on which way you swipe it — similar to notifications in iOS.

While the promise of Ubuntu on mobile could eventually lead to users carrying desktop-level computing power around in a phone-size device, the focus for this first product is clearly on the mobile experience. The phone has dual SIM card slots, which, along with the low price, makes it appealing to budget-conscious customers.

Even if adapting apps to Ubuntu's phone is as easy as Canonical claims, it'll have a tough time competing with cheap Android phones with access to hundreds of thousands of apps. Still, in the lower-end device tiers, Android suffers from inconsistent performance, device fragmentation and security woes — issues that are much less of a concern in nascent platforms like Ubuntu's and Firefox OS. For discerning customers who don't need to run many apps, these curious new devices may actually make some sense.