‘What does it do?’ That’s the question that anyone who cares about the Apple Watch wants answered.

There are a host of answers, and while I’ve not yet found one that’s utterly compelling, this is by far the best smartwatch I've used. It’s the first where I’ve consciously really wanted to make sure I’m always wearing it and that the battery doesn’t run out.

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Designed for life?

First off, like all good watches, the Apple Watch is a luxurious, even beautiful fashion accessory. I’ve spent a week wearing the £599 42mm, stainless steel model with a light brown leather loop band. From the clever magnetic strap to its understated design, it has attracted attention for all the right reasons.

At £299, or even £13,500, it is by no means as expensive as others on the market.

For me, it more than passes the fashion test. I’ve not encountered anyone who couldn’t find a strap and watch combination they genuinely liked, although few have actually had the chance to wear one in real life. I surprised myself by wanting to change straps depending on the social setting or, for instance, using a rubber sport band for exercise.

> > Apple Watch: the Fashion verdict

Set-up and customisation, via the Apple Watch app, is straightforward enough, and it’s where the Watch starts to get smart that it becomes more interesting.

Speaking as someone who doesn’t normally wear a watch, that’s crucial for Apple to make this work.

For a start, the face, which only lights up when it detects you’ve moved your wrist, is almost infinitely customisable. You can have Mickey Mouse tapping his foot to the time, a graphical display of sunrise and sunset, the moon and the planets or a vast array of typical ‘complications’ showing the time in other zones, your next meeting, how many calories you’ve burned or plenty of other options. It’s not novel, but as is so often the way with Apple it takes existing functions and does them better. All this is accessed simply by pressing - ‘force touching’ - a single finger on the time display.

A filter for your phone

There are countless things beyond telling the time that the Watch can also do - but I found that if it was used for every app and message, it became an irritating blizzard of notifications that I quickly started to ignore altogether.

Apple stresses that the Watch is a ‘new way to interact with important, timely information’ - that means there’s never an excuse to miss a phone call again, thanks to the haptic - aka discretely buzzy - sensation on your wrist.

It’s also easy to select the option to answer a call on your iPhone rather than have an awkward speakerphone chat with your wrist. If you look at your Watch immediately after a notification, it shows it to you automatically, and if you hold it for longer it shows more detail. Look at the Watch any other time and you just get the time.

Apps will notify you only of the most important things, if you permit them. The Watch is a filter for your phone, freeing you from the compulsive checking to see if anything new has happened.

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When it comes to text messages, for instance, you can instantly reply via Siri or with a set of intelligent, contextually aware phrases. With so few other Watch wearers while I was testing, it was hard to use the options to tap people on the wrist or to send them pictures or even my heartbeat; but while these ‘Digital Touches’ do feel like gimmicks they are also gimmicks with real, practical uses.

When the Watch is on your wrist, swiping up from the bottom takes you to a set of glances, such as most recent apps, stock prices, the weather and more. It’s an area that feels like it will expand as time goes on and again saves using the phone itself. With the Music app you can control what’s playing on your phone or via speakers.

Interface, apps and battery life

Throughout all of this, the Apple Watch interface is a mixture of using the ‘digital crown’ dial to zoom in and out on a screen that is too small to pinch and zoom, and using it as a back button. The side button brings up contacts.

This sounds complicated, and it does feel complicated initially. I’ve got used to it, but I still occasionally feel there is one button press too many. If the display isn’t on, for instance, it takes two clicks of the crown to get the device to turn on then move from watchface to apps. It’s hard to see how to do it better, but its imperfect nonetheless.

Displayed as a kind of cloud, the apps themselves are surprisingly easy to find.

>> Apple Watch: The best apps

They seldom, however, felt properly developed. When using Hailo I always ended up then using my phone to see precisely where a cab actually was. When using directions, I liked to see the map. A recipe app was simply a tiny-screen version of the tablet option, inaccessible with hands greasy from cooking.

But using the Watch as a remote control for your iPhone camera or Apple TV, or to display a boarding pass QR code, which automatically stays on, is clever and feels like progress.

Even using the Watch intensively, it never struggled to last a whole day, and once made two full days, just.

Health and fitness

For me, it was only in health and fitness that the Watch came into its own.

A set of three rings track how much exercise you’ve done, how many calories you’ve burned and how much you’ve stood, as measured against your own goals. The aim each day is to make each ring come full circle each day. You can look at the data via your Watch or in more detail on your phone. Although it’s disconcerting that the Watch prompts you to stand while also giving you driving directions, it does, in appropriate situations, make a real difference.

A ‘force touch’ can start or stop a workout, which can be tailored to rowing, running, walking or a host of other options. Paired with an iPhone the Watch can use GPS to track a route, or without it will do distance and play music via bluetooth headphones. If you achieve your goals, Apple gives you worthless but irrationally satisfying digital rewards.

Is it worth it?

I’m quite a fan of Android watches. Google Now tells you when to leave so you don’t miss appointments, for instance, and is arguably more useful in many ways than the Apple Watch.

But some older Nokias did more than the original iPhone. Because they failed to adequately combine form and function, nobody really cared.

So with the Apple Watch, again, existing functions are rethought and combined in a new and uniquely appealing way.

That’s not, however, to say that even Apple fans with £299 burning a hole in their pocket should rush out and buy this first generation Watch. It’s beautifully designed and frequently rather useful - but history suggests version two or three will be even better.

The Apple Watch is priced between £299 - £13,500