I recently started using it. It's nice because it comes with E2E encryption and is usable on desktop. Alternatives all have various limitations: Skype (no E2E encryption), Signal (no calls on PCs), iMessage (only usable for Apple users), Wire (requires additional program installation and account creation).
The other device they announced (Surface Duo) is Microsoft hardware running Google software (Android).
Makes sense, as it's really the only way to get into the phone market and still have an app ecosystem.