Having to specify self or cls as the first argument of an instance or class method. This one is weird when you are learning Python because you don't pass in the first variable but it gets magically inserted for you.
Creating a class method using a method decorator. Using a decorator to do something like this seems like a hack to me.
Not having a clean way to specify what all the instance variables are outside of the constructor. People with a java background are used to putting instance variable declarations as the first thing inside a class definition. In Python, these will be static variables. This seems weird and inconsistent with the how method declarations work (methods only become class methods when a decorator is used).
BTW, I like Python.