Now, look, I don’t to stop you from reading this review to the end but I'm going to level with you now because I can't hold back: I love this Apple Watch. It is the biggest step-change by far between iterations of Apple's wrist-born tech. It's not perfect, and we'll come to that, but it's astonishingly good.

For a start it is the most achingly beautiful Watch yet from Apple. It takes my breath away each time I raise my wrist and the screen quickly fades up in full, colourful glory.

If that sounds over the top, just wait until you see one in the flesh.

Seriously, this is not just the most elegant evolution of Apple Watch design – though it's certainly that, too. It takes the design to a new, gleaming level of opulence.

Apple Watch Series 4 review: Screen and size

First, there's the screen, which is significantly larger than before, though the case of the Watch is only 2mm taller than previously. Previous Watches came in two case heights, 38mm and 42mm, but the new Watch models are 40mm and 44mm respectively.

Oh, and by the way, before you ask: yes, all the bands and straps you've acquired for previous Watches will fit perfectly on the new models. Phew.

The difference in size is quite modest, and it doesn't feel any bigger than last year's when it's on your wrist, not least because it's actually thinner than Series 3. And this thinness means that the total volume of the new Watch is smaller than before.

But the new screen size is significantly bigger, to the extent that I wouldn't be surprised if some prospective Watch customers opt for the smaller 40mm size case - this smaller version still has a larger display than last year's larger-sized 42mm model. The display is more than 30 per cent bigger this time.

But the size isn't the only great thing about the screen, it's the edges. Where the Apple Watch display previously was rectangular, like, you know, almost every screen ever, this one has curved edges which follow the shape of the bezel perfectly. Turn on the Watch's torch function for the clearest indication of this: the light fills the screen and its curved edges with their just-right bezel look great.

Apple Watch Series 4 review: Watch faces

Some of the Watch faces have been redesigned to take advantage of the extra screen real estate, especially the Infographic face which has lots of complications and text which curves round to match the circle of the clock face.

There are also advanced visual effects. Since the first Watch with its high-quality animations of jellyfish and flowers, through the additions of Mickey Mouse and Toy Story characters, Apple has made the most of the bright, sharp look to the face. Every previous Watch face is still available, but now there are items like Liquid Metal, which looks like rippling pools of silver or bronze, for instance.

(AFP/Getty Images)

Or the Breathe Watch face which takes the excellent, minimal Breathe app (where you focus your breathing for 60 seconds, for a surprisingly relaxing effect) and turns it into a Watch face.

The faces that haven't been optimised are simply bigger, and that makes them look better as well.

Apple Watch Series 4 review: Colours and finishes

Like in previous years, there are different case materials available. The aluminium finish is the entry-level Watch, then stainless steel is one step up – a process that is mimicked in the iPhone: the most expensive iPhone XS has a stainless-steel antenna band.

The aluminium models come in three colours: silver, gold and space grey, all with an understated, matte finish.

This year, there's no Apple Watch Edition, the high-end Watch that had a gold case in the first year and a beautiful ceramic finish in subsequent years.

I think that's not least because the middle-quality finish – stainless steel – is suddenly especially luxurious. There's the gleaming silvery finish of the regular stainless steel, the shiny-but-understated glamour of the space black stainless steel (still my personal favourite) and a new colour. This is the gold stainless steel finish and it looks tremendous: glossy without being showy, classy but not smug.

I'd expect this to be the runaway success of the new Apple Watch range, but there are more options.

Nike has continued its collaboration with its Nike+ versions in silver or space grey aluminium, available from 5 October. These are effectively special editions, but they are priced as the other aluminium Watches.

The most expensive Watches continue to be the Apple Watch Hermès models with extra-chic straps and special Watch faces.

Apple Watch Series 4 review: Design improvements

The Side button, used to invoke Apple Pay through a double-press, for instance, no longer protrudes from the edge of the Watch. It sits so perfectly level with the rest of the case that you can barely feel it's there, even if you rub your finger along it.

But you can't miss it – just place your finger on the right edge of the Watch and push. There it is. It's big enough that you don't have to be precise where you press and it's very responsive.

The previous side button looked good, but this is certainly a slicker, subtler design.

Just above it is a tiny hole. This, it turns out, is a microphone which has been placed there to be as far from the speaker that runs down the left side as possible.

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That speaker was previously two small slots which were placed one above the other with the microphone alongside. Moving the microphone means the slots sit side by side and are slightly bigger. Which explains why the Watch is much louder than before. Ask Siri a question and you'll definitely hear her response. Apple says it's 50 per cent louder than before but it feels like even more than that. Shh, Siri, everyone can hear you.

All models of Apple Watch now come with a ceramic and sapphire crystal back - previously only the pricier models did. This helps with more than the look: it improves signal transparency for better calls, for instance.

The glass front of the Watches remains as before, that is Ion-X glass on the aluminium ones, sapphire crystal on those with stainless steel.

Apple Watch Series 4 review: Digital Crown

The crown is a useful way to interact with the Watch, rotating to let you scroll up and down lists, pressing in to confirm a selection, for instance.

(REUTERS)

But there's now haptic feedback in the Watch. That's the little vibration which is delicate enough to feel like a gentle press. So, as you wind through a series of elements, like songs in a playlist, for instance, you feel a gentle acknowledgement as each song passes. It's intensely subtle and makes a genuine difference to how intimate and personal the Watch is to use. Listen closely and you can even hear the feedback, sounding like nothing so much as the noise a regular watch makes when it's being wound.

Apple Watch Series 4 review: Connectivity

Last year, the Apple Watch Series 3 brought greater independence to Watch wearers with the arrival of what Apple calls GPS + Cellular models. This meant you could leave your iPhone at home and still be connected so you could receive notifications, make calls, order an Uber, dictate a reminder and so on.

(REUTERS)

This year there are two aluminium Series 4 Watches that lack this connectivity, but all others have cellular connectivity as well.

Last year's Series 3 is still available, with or without cellular connection, but in aluminium finish only.

Apple Watch Series 4 review: Features

Apple has always promoted health and fitness in the Watch but there's a lot more here. Fall detection uses improved hardware (accelerometer and gyroscope), together with advanced algorithms for the Watch to know you've fallen down and alert emergency services. You will understand that I haven't quite been able to test this, but if I take a tumble I'll report back. And here's a neat extra: while you have to switch this feature on, if you've told the Watch you're over 65 it'll turn it on for you by default.

The Workout app has learnt when you're exercising and can automatically start monitoring. You'll get a notification that it looks like you're running, say, and if you agree that you are, it'll start crediting you with run metrics from the beginning of your workout. Handy when you forget. Same applies if you forget to end a workout.

Jeff Williams, Chief Operating Officer of Apple, speaks about the the new Apple Watch Series 4 at an Apple Inc product launch event at the Steve Jobs Theater in Cupertino, California (Reuters)

New for the Apple Watch Series 4 is an attention to low heart rate so the Watch can notify you if it's worried about you. And Apple says heart rate monitoring is faster now, too.

And there's the capability to perform an Electrocardiogram (ECG) thanks to a sensor that's pressed against the skin of your wrist and another in the Digital Crown. Launch the app, press the Crown and it'll start measuring.

This feature isn't live yet as, though FDA clearance has been obtained in the USA, the software is still being finished. When it is, it will be US-only. It will only come to other countries when their medical authorities say it can and remains invisible until then.

Apple Watch Series 4 review: Performance

Every year, the Apple Watch gets faster, so that launching apps is quicker, for instance. That's the case this time, thanks to the new dual-core processor. This is a 64-bit chip, for goodness sake! Who knew a watch would ever have such a powerful brain?

The new processor, matched with watchOS 5 software, means you no longer have to say, "Hey, Siri" to invoke the personal assistant. Just raise your wrist to your mouth and speak. In practice, this worked only intermittently for me at first. I slightly had to learn the movement I needed to make, the speed, the angle and so on which would tell the accelerometer that's what I was doing.

Once I'd cracked that, it was flawless. This feature works on Apple Watch Series 3 as well, by the way.

As does Walkie-Talkie, a cute new way to quickly talk to other people - like when your significant other has gone to the shops and you want to tell them to pick up milk and you just know that a text or email would go unread until they're home again, and how would that help you make a cup of tea, exactly? It's simple and fun: press, speak, release. No need to say 10:4 or over-and-out, but nobody can stop you.

Apple Watch Series 4 review: Battery life

With all these extra demands (bigger display, faster processor, more features) you might expect battery life to have dwindled. In fact, Apple claims the same 18 hours as before. In practice, it lasts a day and a half, I find, and if you forget to charge it overnight, it fills right up again very quickly, while you're showering or having your breakfast, say.

So quick, in fact, that there's no reason why you shouldn't wear it overnight if you want to measure your sleep quality. Third-party apps do this now but, fingers crossed, one day Apple may provide its own sleep analysis. It did buy Beddit more than a year ago, after all.

Apple Watch Series 4 review: Verdict

Last year's Series 3 was great, but this is a whole new thing. The design is just gorgeous and the bright, vivid display with its narrow, curved bezels, looks sensational. The uptick in performance power is noticeable at every level and the increased health qualities and fitness monitoring are hugely welcome.