Yeah Torment Grenade is a situational stratagem but very handy when you need to finish something off with 1 or 2 wounds remaining.
Otherwise, I think they're overall a little worse off than they were in 8th. Blast is nice, but with str 1 it will rarely net more wounds. In 8th, the -1 Ld raised the ceiling of how many models a unit could potentially lose to morale by 1. In 9th, it simply adjusts the likelihood that someone fails in the first place.
Not a significant difference one way or another, but it did increase in cost too. Frankly, it's a terrible gun for 5 points (think of it as D3 poison that always wounds on a 6), so it really comes down to whether or not you make use of the stratagems it opens up.
I think it's worth taking 1 or 2 in a list if you have the points, but it's not the kind of upgrade you'd want to spam.