Allow me to give you the one sentence summary of every single Apple Watch review published today: It's the best wearable on the market, but it's expensive and inessential.

Inessential. That's a potent word to describe any product.. Expensive has never been a problem for Apple--it has always catered to the higher-end of the market. But inessential? For Apple, that could be the difference between the iPhone (which accounts for 69% of Apple's revenue) and the Apple TV (which Apple has always called a "hobby").

I don't think Apple has anything to worry about yet, however. The press said the exact same thing about the original iPad, and that turned out great. Early adopters and Apple loyalists will flock to the first edition of the Apple Watch. But the world's most valuable company will have to up its game next year, when it inevitably releases the second edition of the Apple Watch.

Apple has to address several basic issues. it has to get more companies to build apps for the watch; make sure those apps don't crash; lessen the steep learning curve of the device; and most of all find a killer feature that makes it something people want to buy in addition to their iPhones.

But what is that killer feature? Here are a couple of ideas:

Greatly-improved battery life: The achilles heel of the Apple Watch--and most wearables--remains the battery life. As I've written before, a truly sticky wearable needs to have battery life that lasts a full week in order to create the habit of putting it on without worrying about whether or not the device is charged. Find a way to extend its battery life or, as my friend Jeremiah Owyang suggests, incorporate kinetic charging.

A killer app ecosystem: One could argue that the iPhone's greatest feature is its endless app store, filled with millions of games, productivity tools and distractions. The iPhone has pushed the boundaries of what a smartphone can do because clever developers bought into the iPhone ecosystem. A killer app made by a third-party developer could be exactly what the doctor prescribed.

No iPhone required: A big drawback to the Apple Watch is that it still requires an iPhone and its Internet connection to function. This limits its potential market and its overall usefulness.

I don't exactly know what that essential feature is. But the Apple Watch feels incomplete without it. The first version of any product is always a rough draft, even for Apple. But if the Apple Watch is to gain traction and become a real contributor to Apple's bottom line, it will have to find the feature or two that make it a must-have. Otherwise, we may be talking about how Apple's magic has faded.