I find many of the mathematics articles to be difficult to read. I'll look at a mathematics concept that I think I understand (or even use often), and it will be written in jargon that is completely incomprehensible to me.
However, where Wikipedia really has a problem is in contemporary politics. Anything that is even remotely political is probably controlled by one or another clique of editors. There are opposing cliques that battle over every Israel-Palestine article, or over whether to use the Serbian or Croatian name for village X that existed 200 years ago, or about whether hummus is Lebanese or Syrian or Israeli or Levantine. There are also subjects in which one clique has gained complete dominance and is able to completely control a whole topic area. If you start looking at the edit histories and talk pages of articles on one topic, you'll come to realize how influential relatively small numbers of motivated (and sometimes coordinated, though this is against Wikipedia's rules) editors can be.
That's why I'd take anything that's even remotely politically contentious on Wikipedia with an enormous grain of salt.