Update: We've got the low down on the Apple Watch's biggest competitors. How will Apple's latest wearable fare?

It's been a few months since Apple CEO Tim Cook's "one more thing" announcement was literally up his sleeve: a sapphire-coated smartwatch dubbed the Apple Watch, not the fabled iWatch.

This iPhone-compatible watch was unveiled alongside the iPhone 6 and iPhone 6 Plus, fulfilling the Cupertino company's "new product categories" promise for 2014.

It's not a circular smartwatch like its fashionable rival, Moto 360, but it still features a premium rectangular design with rounded-off corners and works seamlessly with iOS 8 devices.

Here's what we know.

Cut to the chase
What is it? An iOS 8-friendly watch that plays nice with your iPhone
When is it out? Spring 2015 release date
What will it cost? Starts at $349 (likely north of £223, AU$403)

What does Apple Watch do?

Apple's first wearable gadget beams messages, Facebook updates and simplified apps to our wrists, eliminating the all-too-common need to take out our devices to constantly check notifications.

There are more than a dozen ways to interact with the watch, from receiving glanceable notifications, to feeling "taptic" feedback, to summoning Siri, according to the newly released developer WatchKit software.

It's going to become especially convenient to pocket the 4.7-inch iPhone 6 and even bigger 5.5-inch iPhone 6 Plus in your jeans, or to always stow the newly released 9.7-inch iPad Air 2 in a bag.

Is that phone call a telemarketer not worth your time or an emergency from a loved one? The Apple Watch makes mundane notifications easy to dismiss while keeping you in the loop on life's most important alerts.

Apple Watch apps
A handful of the Apple Watch apps being demoed

Other apps seen in the Apple Watch video include iMessages, Health, Calendar, Weather, Mail, Photos, Camera's shutter button, Passbook that now includes Apple Pay and even Apple Maps for navigation.

Developers are now readying more Apple Watch apps thanks to the WatchKit SDK launch. They're being given a headstart with the software and it could bring a whole new section to the iTunes App Store.

The smartwatch also takes cues from the Nike FuelBand SE and other fitness trackers with health sensors and nutrition apps, a must for any serious wearable gadget these days.

Sure there are fitness apps on your smartphone, but you're not always carrying your iPhone while tracking your steps and activity. The Apple Watch is better suited for your everyday workout.

Design

The final Apple Watch design isn't too far from the made-up renders that we've seen in recent weeks. It draws inspiration from iPod Nano with a rectangular-shaped screen plus one knob and a single button.

The Apple Watch is more than iPod Nano meets the iPhone, though. The smartwatch display comes in two sizes measured by height: 38mm (1.5in) and 42mm (1.65in). Both are slightly smaller than the entire Pebble Steel watch height, which measures 46mm (1.8in).

Apple Watch screen resolution
Apple Watch comes in two sizes and two screen resolutions

We also now know the resolution of each screen. It'll come in two sizes: the 38mm Apple Watch will have a resolution of 272 x 340, while a 42mm version will have a 312 x 390 display.

Apple has only revealed the height of its new smartwatch screen, so we can't properly calculate the pixels per inch, and anyone who does is just guessing. But it'll likely rival the 300ppi of the Samsung Gear S.

Apple Watch design
Here's the Apple Watch design from all angles

The Apple Watch's screen is surrounded by casing made of custom alloys of stainless steel and aluminum that, according to the company, stand up to the physical demands of daily wear and another BendGate.

Beyond the "Apple Watch" and "Apple Watch Sport" versions, a special "Apple Watch Edition" mixes in 18-karat yellow or rose gold for a premium look. It certainly goes well with that gold iPhone 5S.

Apple Watch collections
Three Apple Watch 'collections,' each with two sizes

That brings the metal colors to six: stainless steel, silver aluminum, space black stainless steel, space gray aluminum, 18-karat yellow gold and 18-karat rose gold.

Digital crown

The Apple Watch doesn't have a round display like the Moto 360, but the casing does feature a circular knob known as the "digital crown."

This input is unique among smartwatches, but a true classic derived from traditional watches. Apple has of course put a modern-day twist on its functionality.

Apple digital crown
Apple invents a new control scheme using a classic input

The Apple Watch digital crown replaces the pinch-to-zoom touchscreen mechanic used on everything from iPhones to MacBooks, which is too impractical on such a small display, according to Apple.

Rotating it allows you to zoom into your app selection, your location on Apple Maps and a photo from a gallery. Scrolling through dates and stopwatch times is handled by this knob too.

The digital crown also acts as the Apple Watch home button. There's no Touch ID sensor here, but Apple Watch is smartly tied to your wristwatch with an anti-theft passcode required whenever it's taken off.

Conversation button

The button below the digital crown allows you to start a conversation with friends. Pushing it brings up a their contact info photos and zooming into a specific person with the digital crown gets things started.

Beyond calling and messaging Apple Watch wearing friends, you can get their attention with a gentle tap. It vibrates the "taptic" feedback on their smartwatch.

Apple taptic conversation
Communicate with simple vibrating taps or sketches

What's intriguing about this taptic feedback system is that it's said to be more precise and subtle than a vibration everyone can hear. Want to ditch a party? Your friends' secret sign may be three taps on the Apple Watch before bailing. It's an interesting way to get someone's attention.

The Apple Watch goes all Drawesome on us with a bizarre sketch function for light messaging on the wrist. Snapchat became big, why not Swipechat? You can also share your heartbeat with someone in real time, though we're not sure why you would want to.

Apple Watch bands

The variety of Apple Watch bands played better than U2 at the press conference, giving consumers a way to personalize their smartwatch.

Standard straps include Leather Loop that conceals magnets for easy fastening, the leather Modern Buckle and the leather Classic Buckle. There's also a gym-friendly elastomer Sport Band.

Apple Watch straps
Apple Watch straps are easy to swap out

Higher-end metal straps include the Milanese Loop with flexible magnetic stainless steel mesh and the stainless steel Link Bracelet.

The ability to swap the straps without having to use tooling or visit or jeweler is one of our favorite features in the Apple Watch vs Moto 360 comparison.