They haven't necessarily decimated Hezbollah. That means - literally - destroying one tenth of it. What they allegedly have done is killed all of the most senior military figures in Hezbollah.
I wouldn't celebrate what is happening, as such, that would seem ghoulish.
It is also concerning that all this might destabilise the region still further. The full consequences wait to be seen.
However, if this contributes towards reducing or stopping the attacks of Hezbollah on Israel, or reducing or stopping Hezbollah's stranglehold on Lebanon, those would be knock-on positives.