There’s this moment in “Dick Tracy” where the fearless detective, chasing down a villainous gang, taps his magical wristwatch to call for backup. Then, realizing the battery is down to 8% and that cellular isn’t connecting, he ducks under a desk to find a power outlet and futz with the settings.

Poor Dick, he upgraded to the cellular version of the Apple Watch Series 3.

Apple’s latest has all the ingredients of the future we were promised. Crammed inside that familiar flattened-marshmallow rounded square is the power to make calls from anywhere, connect to an always-listening personal assistant and check in on your health with biometric sensors—all without depending on an iPhone for connectivity.

Except, after I spent a week testing these new models—denoted by a red dot on their dials—the future feels even further away. You’re lucky if the battery allows you to roam on cellular for longer than half a day—especially if you’re making calls. And only a limited number of third-party apps work without the phone close by. (No Instagram, Twitter , Uber.)

Most worryingly, my colleague Geoffrey Fowler and I experienced cellular connectivity issues on three separate pre-production models, in two different states, on two different 4G LTE carriers.