(Skip this if you're fine with uploading your data to Connect)
A warning for those who consider ordering a new Fenix 5(X) and expect to be able to use any of the Bluetooth-related functionality (notifications, weather, ephemeris data updates, IQ appstore access, firmware updates) without uploading their data to Connect: it is now official, it is not possible anymore.
Garmin have changed the privacy agreement such that it now explicitly states this clearly: "If your Garmin device has Bluetooth capability and you connect it to the Garmin Connect Mobile app, then the activity data on your Garmin device will automatically be uploaded to your Garmin Connect account." See: new privacy agreement
For the Epix and Fenix 3 there are (partial) workarounds, but as there is no way to know in advance if those will work for the 5(X).
NB the forced uploading is not only a problem for those who don't want data in Connect, it is also bothersome for people who don't have good data connectivity (bad cellular coverage leads to the phone transmitting on full power at every sync, draining the phone's battery quickly).