If you don't have an Apple Watch yet, you should get one. And probably this one. Yes, it may seem expensive and extraneous if your already have an iPhone and maybe an iPad and laptop or whatever, but here's the thing: It can save your life in a way none of that other stuff can.

Roughly two-and-half minutes into my run, the watch kicks in. There's a haptic buzz on my wrist. "It looks like you're working out," the watch face reads. That's followed by a big, yellow button, suggesting I start an indoor run.

Just as Samsung, Google and the Wear OS gang look like they're catching up to Apple, it goes and streaks ahead. The truth is that the Apple Watch Series 4 is in a different league right now, and balances style, features and specs to make an excellent smartwatch.

Better design; Lifesaving metrics; Top sports features

More expensive; Battery life still short; Siri integration still not great

Editor's note (Sept. 24): This review has been updated to reflect more impressions and results of iFixIt's Series 4 teardown .

Big; beautiful display; Advanced health sensors; Faster processing power; Useful Raise to Speak Siri

ECG app not available at launch; Expensive

Apple Watch Series 4 has moved the smartwatch to an all-new level and it provides an excellent companion for anyone who wants to keep an eye on their health, their fitness and wants to stay connected with or without their iPhone by their side.

Great design; Larger screen; Cellular connection; Heart sensors; Fast and responsive

No third party watch faces; No roaming with cellular

Apple Watch Series 4 is the best reason yet to buy a smartwatch

Sleek redesign, Huge, gorgeous screen, Novel health features

Significantly more expensive than Series 3, No always-on display option

If you already have an Apple Watch, should you upgrade That depends. If you own a Series 3, I wouldn't rush to trade it in unless you use it to make calls all the time or see the upcoming ECG feature as a must-have feature.

Large screen; Good call quality; ECG capability; Fall detection; WatchOS 5 brings numerous improvements; Stylish

Expensive; Battery life remains unchanged; No built-in sleep tracking

The fourth iteration of the Apple Watch still looks like a tiny iPhone on your wrist, but for many, it was the most exciting device announced at Apple's event earlier this month.

Bigger; better screen; All old Watch bands fit on the Series 4; Good battery life; Faster performance; Fall detection has the potential to be lifesaving; ECG features give users more control to monitor their health on a daily basis; Accurate auto workout detection and ending feature; WebKit support...

ECG app isn't available yet; WatchOS 5 drops support for Series 0 devices; New complications are only compatible with new watch faces; Still no support for third-party watch faces; Still no native sleep tracking; Siri has trouble completing Shortcuts; More expensive than any other Apple Watch; and...

Has there been a learning experience for Apple quite like the Apple Watch Back when the original model launched in 2015, there was – not unfairly – a sense that Apple itself wasn't quite sure what exactly it should do.

Mesmerizing new display; Fast and smooth performance; Health features could be game-changers; Battery life hasn't suffered

Siri still falls short; Expensive

Apple takes unjustified heat for iterating on a product year after year. By not tossing out the whole platform and design, however, the company has created a game-changer with the Apple Watch Series 4.