There is a very interesting book related to this subject, "Commanding the Red Army's Sherman Tanks: The World War II Memoirs of Hero of the Soviet Union Dmitriy Loza". Very well written and well worth a read, btw. Loza, started as a lieutenant in the Red Army tank forces in a unit equipped with American M4 Shermans. He and his men liked the tanks quite a lot actually. He praises them for their reliability, build quality and the spacious cabin.

I's been a while since I read this book, but I do remember once incident that Loza describes where his tank was disabled in the middle of a battle. He and the crew were completely pinned down, and couldn't retreat on foot, and the tank was burning. The only thing they could do was crawl under the tank to shield themselves from machine gun fire but they expected the tank to explode sooner or later so they resigned themselves to death. However the tank didn't explode and the entire crew lived.

From what I remember, Loza didn't consider the Sherman to be inferior to the T-34 in any way.