To understand why you might want the new cellular Apple Watch, put yourself in the shoes of a wealthy person who drives a weekend car. (I promise this is a fun exercise.)

In this situation, your iPhone is like your everyday workhorse vehicle, with the muscle to speed through emails, calendar invitations and social media posts. But when it comes time to unwind, you can leave the house with just a cellular Apple Watch — the equivalent of the weekend car — and still have access to a lightweight phone that can handle calls and text messages.

In other words, wearing the Apple Watch Series 3 with cellular connectivity, which Apple will release Friday, is like owning a leisure phone that is excessive but situationally useful. Apple’s first wearable to include cellular may come in handy when you are at the gym and want to leave your phone in the locker, or when you go out for a run and want to remain reachable.

After testing the cellular watch for a week, I found it to be an excellent smart watch that is a significant improvement over the first Apple Watch, which was slow, confusing to use and deeply flawed.