It all depends on what you're trying to accomplish in showing the time. As pointed out before, almost every screen on every device is already showing the local time (usually digital). Are you showing a different time zone? Are you showing remaining time until some event? In other words, is there a need for a different time?
The next question is, are you trying to show a time precisely, perhaps to the second, or does the viewer just need to know if it's time for lunch? A subset of this is whether the viewer is interested in time intervals (time until X), or just the current time? I wear an analog wristwatch with a digital day-of-month, because I usually don't need to know the precise time to the second, but I often have a need to know an approximate interval: "It's about 30 minutes to lunch. I'm 5 minutes overdue for a meeting. 3/4 of an hour to quitting time.". Etc. By position of the hands, and where they "need" to move to, I can quickly tell an interval. Long ago I wore a trendy digital wristwatch, and I had to stop and do math to figure out an interval. However, the date in digital form is useful, as I usually want to know that precisely, rather than interpolating between marks (as with some fancy chronometers).