It saved his life today 100%. It has already saved potential major injury too in Spa 2018 when Alonso's car hit the halo and not Leclerc's head.
Nico's crash - he even admitted himself he wasn't sure if the Halo was even in his way (https://www.theguardian.com/sport/2018/ ... prix-crash
) and the car did catch fire with that one. All be in no where near today.
Stroll crash today - non issue, he was able to escape easily. Easiest of the three.
Grosjean by far had the hardest escape of all three in the worst circumstances and was able to do so.
Could it be made easier? I have always been surprised they haven't looked into the sides being able to release if needed.
Personally though I think the focus of investigation from todays will be the barriers. That should not happen in 2020.