How was German artillery compared to US and Soviet? German artillery seems rather inferior overall, with an inferiority of shells but more built along US lines.
The Soviets had quantity but not much else. The typical infantry division's artillery was mostly the 76mm gun. This was organized into two 6 gun batteries along with a 122mm howitzer battery per battalion.
Soviet fire control for these batteries was for the battery commander to establish a forward fire control post that allowed direction of his battery. This single position was the fire control for most batteries in action. Direction was usually by dedicated field telephone but sometimes radio.
The system was inflexible and incapable of generating unplanned mass fires. But, it did generally result in some fire being brought on the enemy much of the time. This is where German histories tend to note how the Russian artillery was always dropping some rounds on their positions.
The Soviets also manufactured alot of "poor man's artillery" mortars. These were cheap supplements to regular tube artillery. They were used in much the same way as their regular guns were.
The major German problem was simply a lack of tubes. This was excerbated by the wastage of guns in the East through non-combat losses. The German artillery system was to allocate some batteries to each combat unit in the division. Massing fires like the Allies frequently did was possible but only with alot of planning in advance.
The Germans also used a tactic with mortars and artillery of having a "roving gun." That is, one mortar or gun from the battery was detached and would open fire from a different location during battery displacements. This gun was intended to deceive the enemy that the battery was displacing and as to its new location.
The Germans rarely seemed to keep their artillery units up to strength. I think that was a mistake. They also made widespread use of captures in many areas. The substitution of mortars and rockets was also a mistake. These are less effective than regular artillery.