The Verge has a good review of the Apple Watch Series 2, but everything seems to be left over when you read the first line of that text:

Let’s call it what it is: a fitness tracker.

That’s almost exactly what the Apple Watch is. I would say it’s what it wants to be first, although it can be a lot more. What it matters is that Apple seems to have found what it needed to convince people to buy this device.

You should buy it because it can help you to be in better shape. That’s it. Other makers use that reasoning to sell their fitness trackers, but Apple can at last compete in similar terms with those products while adding all the other neat options the Apple watch gives their users. Joanna Stern, by the way, has also expressed the idea in a fair way:

Still not a ‘need’, finally a ‘want’.

Not much to add after those two little sentences.