A weakness of communism is the low incentive to work. Because everyone is making the same wages, doing the same things, I think the level of quality vs. quantity in pretty significant. The products are low quality, but they aren’t expensive.
A strenght I believe communism has is the fact that there is some level of equality. In other words, no one is richer than the other person. Everyone is considered to be the same class, so it’s not like there’s really much of a reason to fight for anything. The leaders who are in fact considered a higher class are of the few, so they aren’t really a problem to the citizens.