- The indentation based syntax: it can easily trip you up when moving big blocks of code around. You want to put this if else block somehwere else, hope you get a syntax error, because you can get sth. that seemingly works but does not do what it's supposed to do. Also sometimes finding where you are can be difficult.
- Dogmaticism: a big thing in the community. They'll wait 20+ years until they add string interpolation, a feature common in many similar languages. They'll wait 20+ years until they start to realise having expression equivalents of statements is useful.
- Breaking syntax: new syntax is added in what seems to be minor releases, so you either avoid new syntax to be compatible w/ all the 3.* interpreters, or you need to expressly avoid certain interpreter versions. And there's no equivalent of Perl's "use v5.something;" so you need to write code juggling multiple supported versions.
Still I think it is a nice language to have in your toolbox for the vastness of the stdlib and the available 3rd party packages.