Better Microphone
The Apple Watch Series 5 also carries over one other small improvement from the Series 4 that many users aren’t aware of, and that’s improved microphone placement and design, meaning that your calls and walkie-talkie chats will sound better in both directions, plus Siri will hear you more clearly.
As a result of this change, plus processor and sensor improvements, the “Raise to Speak” feature also works much more consistently and reliably on the Apple Watch Series 5 than it did on the Series 3, and if you use Siri a lot, that alone may be well worth the upgrade, especially if you’ve also got a HomePod listening in or you’ve simply grown tired of having to say “Hey Siri” before every request.