As a TA, how should I address the professor's difficult curriculum?
Begin with the assumption that there are good reasons for the change: professors rarely make a large change in a course without thinking about why (it's just too much work to bother).  Rather than beginning with your judgement (which might or might not be justified), open with an observation and a question, something like:


  I was looking at my old notes, and I've noticed that the examples have changed a lot and gotten significantly more complex.  I was wondering if you could tell me a little bit more about how you've changed the course and why?


Maybe the professor actually wants the class to be harder; maybe they just wanted it to be more current and don't realize it became harder as well; maybe you are overlooking something... all of these are possible, and until you understand how the professor is thinking about it, you don't have enough information to figure out how to proceed.