There's also the Camera app on the Apple Watch. That seems strange at first since the smartwatch doesn't have a camera. But the app is quite useful: It's a remote control for your iPhone's camera, so you can take a shot without jostling the iPhone or being so obvious. If you put your iPhone on a stand or mini-tripod, this app is seriously convenient to shoot your photos.
An obvious app found on every smartwatch platform is weather: What's the temperature and outside conditions for where you are or where you're going? The Apple Watch provides a lot of weather detail in its Weather app, and for whatever cities you've set up in your iPhone's Weather app. Its glance view is also wonderfully focused on what you need to know right now.
As you'd expect, Apple's Passbook app makes airline and other tickets, as well as Apple Pay, even more convenient.
But Apple is not the only provider of useful apps that take meaningful advantage of the smartwatch notion. The Delta Airlines app not only shows you the status of your upcoming flight (which the JetBlue Airways and United Airlines apps also do), but also your plane's location during the flight and where your baggage is when you land. This is useful info to get, and info you may want when reaching for your smartphone isn't so convenient.
The middling: Apple Watch apps that don't quite deliver
Unfortunately, there are more middling apps, including some from Apple, on the Apple Watch. These apps are the ones that make you wonder if the Apple Watch really will be the next iPhone or iPad, whose potential shows its reality after developers start taking real advantage of its new context, or whether it will be a niche, faddish product like every other smartwatch to date.
Take Apple's Mail app, for example. It can be useful to see incoming email subjects on your wrist, so you can decide to pull out your iPhone, iPad, or laptop to address whatever is going on.
The Apple Watch app on the iPhone lets you select which email accounts are shown on your smartwatch, as well as restrict shown emails to people in your VIP list or to new emails in existing threads. Apple has nicely adapted its gesture for quickly deleting emails, as well as for calling up the options to flag an email or mark it unread.
But the core of using email is reading and responding, and neither is easy on the Apple Watch. You really have to use your iPhone or other device. As a result, the Mail app on the Apple Watch comes across as promising more than it can deliver. I almost wish it was restricted to only showing subject lines notification-style.
Sign up for CIO Asia eNewsletters.