There are issues with the Garmin Connect for Android:
1) There's only two methods to set the heart rate zones - %max HR and BPM. The watch has %HRR, which I prefer.
2) The settings always default to BPM when saving the app and always reset the settings on my watch, screwing my heart rate zones every time.
3) The Garmin Connect web app only has BPM and %HRR.
This is a very inconsistent experience, which does not let me use the product hassle free, I have to keep checking the settings in the watch after each sync, so that I get the right heart rate zones.
For an inexperienced user this could have a huge impact, if he/she trusts the heart rate zones shown by the watch, which have been then screwed up by the Android software.