Apple watch with cellular question

You still need to pair your Watch with your iPhone. After that you can leave your iPhone at home and use your Watch to receive and make calls and messages, etc. You still need to connect to your iPhone daily.

There are still a number of things that the Watch cannot do without the phone. You don't have access to Safari, some 3rd party app notifications require the phone to be powered on and connected to the network. Some photos in messages cannot be viewed on the Watch, and the eSIM in the Watch requires the iPhone to be programmed and cloned. Storage on the Watch would be an issue, and the Watch cannot roam cellular networks at this time. The Watch also requires the iPhone for backups. Given the restrictions of a device that size, I think they have done pretty good at it performing how it does with out the phone.