It has to be part of a bigger connected picture. Apple's always been uniquely good at building devices that work well on their own and better together, and the iWatch needs to be the best example yet.

No, Apple's not going to make an iWatch that plays nicely with your Android phone or your Windows PC. That's fine. What it needs to do is build a device that is powerful and useful in its own right, and becomes even more so when it's paired with other Apple devices.

The iWatch needs to be a key part of a powerful fitness ecosystem, using Apple's Health platform to integrate data like steps and heart rate into your other measurements. It should be the hub of your smart home, allowing you to turn off your lights or change the temperature without needing to pull your phone out. Maybe without even being connected to your phone in the first place. It should be able to control your music and your Apple TV; it should be able to pay for things and unlock your laptop. (Oh, and it needs to be able to grow into doing all that without becoming a user interface nightmare.)

I should be able to use Evernote for taking notes, Lyft for calling cars, Spotify for music, Google for maps, and anything else I choose. A watch is personal; it's not good enough if it doesn't work the way I do.

It needs a killer app — and a lot of other ones. The iWatch won't be the same thing to all people. Medical professionals are already thinking about ways to use smartwatches, while frequent travelers or gamers might want something else entirely. Personally, I want an easy way to see and act on notifications, quick search and note-taking tools, and easy ways to check in on Foursquare or tweet about the weird dude in front of me on the train who wishes he could live at the bottom of the ocean. Just as the iPhone's popularity only truly bloomed when the App Store launched, the iWatch needs to be as versatile as it is powerful.

But at first, the iWatch also needs a single primary raison d'être, a reason for being in the first place. Maybe it's about health, offering step counting and sleep tracking to fitness-conscious consumers. Maybe it's about payment, or home security, or notifications. The iWatch needs a single revolutionary story Apple can tell about what it is, why the world needs smartwatches — and why they need this one. No other manufacturer has figured out how to sell their smartwatches, how to convince users they need one. Apple needs to get it right.