Soviet tanks were usually very good tankwise, but lacking in softer stats. Their big problems were that they needed to arm a huge conscript (or even worse, draftee) army, so they hoarded everything past obsolescence and most of it was below standard (T-62 wasn't that good even back then, but they're still in service) and the lagging electronics industry meaning their night sights, FCS, and in particular thermals were awful. There's solid argument that until the advent of NATO "box" tanks and the Rheinmetall 120mm soviet designs were better than everyone elses, but beyond they were quickly overtaken.