Ok so, my take..
-It happened in the blink of an eye, no time for Mayday, etc.
-Given mode of failure, rotor head twisting off, epicyclic gear breakdown is likely.
-The HUMs probably did not indicate pending failure before flight. (..but HUMs data could have been misinterpreted)
-More details will trickle in over the next few months, years, before final analysis.
-Accident happened within one of the most professionally run organization in helicopter industry.
= H225 grounded for a long time (maybe forever)//confidence shattered