It comes quite early and is cheap at 270 manpower.
It has the biggest arc (+/- 40° to each side, others have +/- 30°).
It shoots rather fast (bit slower than PaK, faster than ZiS).
It has an acceptable (115 / 125 / 140) penetration that allows you to fight low-tech vehicles. This penetration massively increases when it vets up. At Vet3 it's (149.5 / 162.5 / 182) and if you pop the AP rounds at that level it's (224.5 / 243.75 / 273). That's sufficient to pen almost everything.
It has 60 range and at Vet1 gets 70 range with the ability.
Now why do these things make it great? It's one of the most cost-effective ATGuns. Due to the big arc usually one ATG is sufficient to cover a part, where others often need two. The pen is sufficient to take on the light Oberkommando vehicles, and Ostheer HTs and the Ostwind. Against the Stug (140 armor) it also penetrates rather often, only vs PIV you should pop the AP rounds. Usually one (or at least two) penetrating shells will already give you Vet1 at which point in time it covers an area almost as big as two other ATGs*. Besides that just think about it. 70 range - that's as much as an Elefant or an ISU-152. Due to it's really low cost it will vet up quickly and at vet3 with popped AP rounds it can combat even the Panther or German heavy tanks. Still at just 270 value.
Those things offer a protection comparable to the other anti tank guns in all stages of the game at a far lower price point. Yes, losing it hurts more as a fresh one lategame is not as good, but with the additional free MP / popcap you should be able to field something to protect it better

*For the mathnerds:
circle_radius(70) * 80/360 = 3420
circle_radius(60) * 60/360 = 1885 (*2 = 3770)