I like many things about my Edge 830, eg following a planned route and the astonishing battery life, but I have found several frustrating issues.
In the 10 days of use my 830 has measured the VO2 max several times yet none of the results have appeared on Garmin Connect. Also, the synchronization between my Forerunner and 830 is really poor. After 7 days the training load on one is over 800, and on the other it is just over 600 so the load is either too high and I should rest, or optimal. At times one device says I am unproductive, whilst the other says I am productive. Several times the Garmin Connect site did not agree with the devices so I have seen three different evaluations of my efforts. I hope the sync issues get sorted soon, along with the on-device route planning which gives worse results than my old 810.