The lock screen shows the carrier on top, the time at the bottom and a column of notification icons along the right side. Pulling the screen down reveals a menu -- the further you pull, the more menu items you see. This is accompanied by audible and tactile (haptic) feedback, which lets you "feel" which item you're selecting. Once you've highlighted the right menu item, just release your finger to select it. While difficult to describe, this gesture is extremely intuitive. It forms the basis for all menu interactions in Sailfish OS and allows easy one-handed operation regardless of screen size. The lock screen menu provides access to things like the phone app, camera app and profiles. Pulling the lock screen up lets you peek at detailed notifications, including the signal and battery status -- sliding all the way up unlocks the phone.

Once on the home screen, you'll find a customizable row of four icons at the bottom -- these are your commonly used apps. The empty space above is reserved for a grid of cards that represent each running app. As such, Jolla's using the home screen as a task manager. Sliding the home screen up reveals the launch screen, a traditional grid of app icons. Pulling the launch screen up reveals a menu with a single item that lets you return to the home screen. Launching an app is as simple as tapping an icon. Navigation is gesture-based -- pulling the screen down reveals the app's menu, swiping left to right replaces the back button. There's also a "depth indicator" in the top-left corner of each app that shows how far down the app's rabbit hole you are. Tapping this indicator takes you back up one level (this is useful when swiping back might interfere with other app controls).

Inside an app, "pushing" left from the right edge of the screen lets you peek at your notifications, while sliding all the way to the left brings you back to the home screen. Minimized apps appear as cards on the home screen but are still running in the background (Sailfish OS supports true multitasking). Cards can be customized by developers to display a UI with real-time info and controls. For example, while the card for the contacts app consists of static pictures of your friends, the card for the media player shows track details and includes play / pause and next track controls. Since tapping on a card results in maximizing its app, card controls are gesture based -- pulling right on play / pause and "pushing" left on next track triggers the appropriate action in the media player.

Another unique aspect of Sailfish OS is the ambience concept. Like with other platforms, you can personalize the lock and home screens by selecting an image from the gallery. Jolla takes things a step further by customizing the color of UI elements (including fonts and menus) to match the content of the picture you selected -- not unlike Apple's album display mode in iTunes 11. A blurred and dimmed version of the image even becomes a background overlay for the launcher and the apps. It's completely seamless and it looks great. Overall, we came away reasonably impressed with Sailfish OS, despite experiencing only a fraction of its functionality. Performance was decent considering the N950's relatively modest single-core underpinnings -- then again, MeeGo's no slouch either. Obviously, we'll reserve judgment until we have the opportunity to play with the final product sometime in Q1 2013.