I've only been using the new Apple Watch Series 5 for a few hours, but I can already tell its new display is going to be a game-changer

While you certainly don't need a compass to get from point A to B in 2019, having one definitely makes it easier to do so. The most useful application for the Apple Watch Series 5's compass will likely be the watch's Maps app, since it makes it possible to view the exact direction you're facing so that you can make sure you're going the right way. That can be especially useful for those who live in big cities and often travel by walking or taking the subway, as well as hikers that want to make sure they're staying on the right track.

The Apple Watch's always-on display and built-in compass make the watch much more useful when it comes to two important use cases: telling the time and getting directions.

But if you have a Series 4, you shouldn't feel compelled to upgrade. The always-on display is the Series 5's most appealing new feature, but that alone doesn't justify a $400 purchase. The Serie 4 and 5 share many of the same features otherwise; they even feel the same considering they're both 10.7 millimeters thin and essentially offer the same speed and performance.

I'd give the same advice to most people thinking about upgrading from the Series 3, unless features like the ability to take an electrocardiogram reading and detect hard falls are also of high priority to you — both of which were introduced on the Series 4.