I find them kind of meh unless you put them in a jeep, where they become super OP.
Basically this^ The issue is probably a combination of fausts not working correctly vs WC51, thompson DPS curve, raketen etc. I think the unit might perform a bit better if they had slightly better RA base and couldn't cheese with the WC51.
What adamircz said. It's decent, it's your only access to smoke outside of luftwaffe, and it does its job now finally after years of being in the nerf bucket. But it is locked behind tech, and it's the less favored tech. I'd use the bulletin slot for something you use more on a regular basis. Volks probably.
I always thought it was pretty good. The strength of it was its shell land in very quick succession. So yes there needs to be a delay before those shells hit, otherwise it'd be OP. Also, major arty is amazing.