Fine, unique tools for Soviets: Shocks, heavy mortar, maxim, bombard ability on tank destroyers and anti tank guns, T 70 which is awesome against infantry and can take a punch (though not a big one), partisans (spawning from buildings, cloak, panzerschreck and mines! Hell what an awsome combination!), radio intercept, very versatile Cons (though with bad scaling but still with a lot of uses), etc.! Really there are some great replays and casts out there where you can see the many possibilities Soviets offer. They really have a lot of great tools!
Shocks are not that uniqe. Game is full of such close-combat anti-infantry squads, like Rangers or Commandos. They are not that survivable, but survivability of shocks is not that awesome too. Obers are still better as Anti-infantry soldiers.
Heavy mortar is also not that uniqe. US Pack Howitzers and LeIGs works pretty same - long range, nice damage and also penetrates vechicles. Lesser AoE maybe, but still - penetrates vechicles. And don't forget about heavy mortrars in mortar emplacement.
Maxim is uniqe, but it's bad HMG (personal opinion). If there would be DShK in stock, then I would be soooo happy.
Bombard ability is uniqe, but for AT it costs 60 ammo! Not always worth it. And for SU-76 it is awesome, but very random. I prefer more armored StuG G, without barrages, but with HP and armor.
T-70 is not that uniqe, lol. Luchs is also nicely dealing with infantry, specially soviet, which doesn't have infantry-AT, like PTRS in stock. T-70 can be destroyed with 3 schrecks hit. Or 222 cars. And don't forget about Stuart. That one at least can be usefull as support, stunning enemy tanks. Valentine sucks, we all admit it.
Partisans are only doctrinal. And those doctrines themselvs are not that awesome. I prefer to have T-34-85 or IS-2 instead of bunch of infantry. More usefull in late, when axis becomes really dangerous.
Radio intercept is uniqe, but it doesn't win battles. Ok, you know that enemy got Panther or King Tiger, what next? You still don't have BS-3 or SU-100 for to deal with them. ISU-152 not always penetrates Panther, for example, lol.
Cons are not "versatile". Riflemans are, Tommyrifles are. But not cons. Those 2 can get LMGs, AT guns, Tommies can be upgraded with healing+survivability or arty+vision. That's real versatily. Cons can only have their poor rifles as weapons, unless you take some "shitty" doctrines with PPSH or PTRS. I don't get it - all factions getting weapons without doctrines and only USSR only with. Really nice for "offencive-only" faction, thank you, Relic...