I think he mentions at least one: public access of instance variables. It would probably be better in most cases (large systems) to just make them all private,

I think he mentions at least one: public access of instance variables. It would probably be better in most cases (large systems) to just make them all private, if you had to choose between private or public. Python can have its own conventions though, separate from the conventions of other languages. It just means the applications that Python is a good choice for are not exactly the same ones that Java or C# are great choices for.