The new Apple Watch Series 6 is the best all-around smartwatch, but don't buy it just for the blood oxygen sensor

Key Points
  • The Apple Watch Series 6 is the best smartwatch on the market, but it's an iterative update over last year's model and is best for new buyers or people coming from the Series 4 or earlier.
  • You can't really think of a new Apple Watch model the same way you do a new iPhone.
  • Canalys expects just 150 million people will have smartwatches in 2020, which isn't that many. But, despite the coronavirus, people are buying them.
Apple Watch Series 6, the new Memoji face looks like me.
Todd Haselton | CNBC

I've been testing the new Apple Watch Series 6 for the past week. It's very similar to the Apple Watch Series 5 launched last year. It even looks the same, unless you check out the new sensors on the bottom or buy one of the the new red or blue models. 

You can't really think of a new Apple Watch model the same way you do a new iPhone. People buy new phones every couple of years, while the smartwatch market is still just getting started. Canalys expects only 150 million people, total, will have smartwatches in 2020. By way of comparison, Apple was regularly selling more than 200 million iPhones a year up to 2018, when it stopped reporting unit sales.

But people are buying them, even during the coronavirus pandemic and extreme economic uncertainty it's created — Canalys also said shipments grew 12% in Q1.

So when I think about the new Apple Watch Series 6, I'm still thinking about people who've never owned a smartwatch and want to take the plunge. For that audience, it's the best smartwatch you can buy, although the $399 starting price isn't cheap, and Apple does offer some less-expensive options.

Apple Watch Series 6 in blue
Todd Haselton | CNBC

The Series 6 does have some options that could spur some upgrades from previous versions, like an always-on screen that gets slightly brighter when you tilt your wrist, which is great for checking notifications or looking at the screen when you're outdoors. It's faster than last year's model thanks to a new chip. It also has a new blood oxygen sensor, but this is meant as a "wellness feature" and not a replacement for a medical-grade device, so don't buy it for that reason alone.

What's good

Apple Watch Series 6 in blue
Todd Haselton | CNBC

The Series 6 is a hair faster than last year's Series 5, opening apps about one second faster, and has a brighter always-on display, which helps when I'm outdoors. These are great if you're a first-time Apple Watch buyer and want the best model, or if you're coming from an earlier version that doesn't have an always-on display and may be starting to feel sluggish. But if you have last year's model like I do, those aren't enough reason to upgrade.

I like that it has all of the features introduced in earlier models, like the electrocardiogram option, and provides high and low heart-rate notifications (as the cheaper Series 3 and Series SE do).

The biggest new feature is a blood oxygen sensor. It's easy enough to use: just open the app, rest your arm on a table and it'll read out your oxygen.

But I don't know what I'm supposed to learn from it. Sometimes it says I have a 96% blood oxygen saturation. Sometimes it says 99%. I don't really know what that means, and Apple doesn't explain beyond that anything above 90% is normal.

Apple says you might want to use the sensor at high altitudes, like during a hike, to see how you're adjusting. But you shouldn't use it for medical purposes, like if you think you might have coronavirus and want to watch your oxygen levels. For that, you should get an FDA-certified device.

Apple Watch Series 6 in blue
Todd Haselton | CNBC

Apple is running three different studies to see how oxygen saturation levels can help people understand their health more. But, for now, don't use it for medical purposes.

I like the new blue color, which is fun but not too shiny and not too bold like the red model. I appreciate that the colors are offered in the most-affordable aluminum tier, which starts at $399.

If you can spend more, I recommend stepping up to a stainless steel model, since those models and higher (titanium) come with the harder sapphire screens that are way more resistant to scratches than the glass on the regular Series 6. Stainless steel models start at $699 but include cellular sensors, too, so you can place calls, receive texts or stream music without an iPhone nearby.

Apple Watch Series 6
Source: Apple

Finally, the Apple Watch software is still the best of any smartwatch on the market. It's fast, there are thousands of apps that you can bring up on your wrist, and it's a lot of fun to try to close the rings that indicate whether you're getting enough exercise and burning enough calories. All the models work with Apple Pay so you can tap your watch to buy stuff at the store — particularly convenient during the coronavirus pandemic, when you might not want to touch a payment screen.

I'm also excited for Apple Fitness+, which launches later this year and will provide workout stats right from your Apple Watch, like your heart rate, on an iPad, Apple TV or iPhone, while showing a workout video.

What's bad?

Trying the blood oximeter.
Todd Haselton | CNBC

My biggest complaint is battery life. Apple still promises 18 hours of on time, which is fine but not great considering Fitbit and Garmin offer many days of battery life. But Apple wins against those with way better software.

At least the Series 6 charges in 1.5 hours, versus 2.5 hours for earlier models. In my case, I just charge it while I'm reading in bed at night and put it back on before bed to use the new sleep tracking feature (also available on earlier models.) I'd love to see two or three days of battery life in future models.

This new band doesn't have any clasps, just slide it over your wrist.
Todd Haselton | CNBC

It's a little boring that it still looks pretty much the same as the Series 4 and the Series 5 Apple Watches. On the other hand, I'm not sure what Apple needs to change. It can't really slim it down while also adding a bigger battery, for example.

Finally, one of my editors has an Apple Watch Series 6 and noticed that the screen didn't always register to his taps. I didn't notice this on my unit, but it could be some software bugs that will be worked out over time.

Should you buy it?

Apple Watch Series 6
Todd Haselton | CNBC

It depends who you are.

If you've never owned an Apple Watch and want the best, get the Series 6. You won't be disappointed.

If you want to save some money, consider the Apple Watch SE, which starts at $279. You'll just miss the always-on display, the slightly faster processor, blood-oxygen tracking and faster charging. But you still get water-resistance, the great software, automatic fall detection, an always-on altimeter and everything else from older models.

If that's too expensive, you can even go with an Apple Watch Series 3, which starts at $199, for the basics.

CNBC tech product editor Todd Haselton looks at Apple's new watch, iPad
CNBC tech product editor Todd Haselton looks at Apple's new watch, iPad

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Correction: Updated to reflect correct price of Apple Watch SE.