The new Apple Watch models go on sale on Friday.

It's the first major redesign of the product since Apple first released it in 2015. The Apple Watch Series 4 has a bigger screen and new health sensors, and it's thinner too.

But specs don't really matter in day-to-day use. What matters is how the watch works — especially considering these models start at $400, a steep price for a watch or an iPhone accessory.

Apple lent a bunch of bloggers and publications new Apple Watch units ahead of Friday's launch, including TechRadar, CNBC, Hodinkee, The New York Times, USA Today, The Sydney Morning Herald, Women's Health, BuzzFeed News, TechCrunch, and The Verge.

In conclusion: It's a great gadget for fitness fans, but people with older models may not need to upgrade.

Here's what they had to say.