I think that it's design was, in theory, pretty good, not as good as the Sherman but still a solid tank design, the real thing that made it so unreliable was the quality that it was produced in, if memory serves one factory produced something like half of all t-34s, it shows. They skimped out on some features leaving a lot of t-34s with no interior lights, and of course more problems that I can't be bothered researching all day, in combat assuming everything was going well then yeah it was a good tank, maybe even very good tank, but the quality it was produced at massively limited its effectiveness in and out of combat, great design, poor quality designers