Conclusion:
+ Very easy to operate
+ Thanks to smartphone apps and featured a 400 GPS Clock
+ Promises thanks Bluetooth Smart 4.0 (Bluetooth Low Energy) longer battery life than its predecessor of 1.Generation "Polar Bluetooth WearLink"
+ Also convenient is that the battery status is displayed in the app.
I can therefore only recommend buying.
Preparing for Bluetooth 4.0:
The Samsung Galaxy S2 i9100 you have to update with the Cyanogenmod Installer since Samsung itself no longer maintains the software.
Currently is thus 10.2 CM (Android 4.3) installed; ClockworkMod Recovery as plus 2.nd stage boot loader. This is as simple as it used to with Samsung Kies.
Those who want to can also registers ZipFile on CM11 Milestone 8 (Android 4.4.4) upgraded what doku loud but is not necessary because already Android 4.3 Bluetooth 4.0 LE support.