Having watched a documentary i agree that this soviet offensive is sorely neglected compared to other WWII battles. I didn't even know of such a massive offensive operation. Significance of this battle is that the landmass the size of western europe was conquered in days & the immense logistics to move mass quantities of men & supplies from european front to the far east with much of it in secrecy.
The battle also resulted in a northern communist North Korea & the capture of Kurile & Sakhalin islands from the japanese.
What struck me was that the battles raged on even after their american allies dropped 2 atomic bombs on Japan. Japanese forces were steamrolled by the red army since most of its heavier equipment & better units had been transferred to the Pacific front.