[narwan]

I use it a lot. It's hugely effective in the game. When I started playing (spww2) I soon noticed many of my units ended the game with lots of ammo to spare. That was especially true for tank HE rounds and mg rounds (from any type of unit). Which seemed a bit of waste 'cause I spend the points buying that ammo. That's one of the things where game and reality differ, where in reality you might want to save ammo for later use, in the game there is no later use. When the last turn is done it's done. You can kiss the ammo byebye.

So my gameplay soon moved towards an ammo-based doctrine under the assumption that the only wasted round is a round not fired and that points buy 'ammo packets' and units are essentially just ammo delivering systems. Some have a multiplier effect on others though (trucks for AT guns is a good example, or artillery observers) which makes them useful too. But even their use is to help others 'deliver their ammo'.
To spend the ammo I had bought I used lot's of area fire. And because I used a lot of area fire I kept on discovering other uses and effects. And still do.

As to units not firing back, a UNIT most spot the firer and pass some sort of roll to fire back and the areafiring unit most be within the reaction range. If you target a specific unit with direct fire there's a good chance it'll fire back in selfdefense. But area fire never specificially targets, so doesn't trigger this reaction fire.

Drifting area fire which goes into hexes out of LOS is indeed a (small) problem. Not because it's 'impossible', but because that effect can be 'abused' within the game. What it means is that you can use area fire to 'shoot around corners'.

Narwan