I have used FCC now for around 6 months now, and have just recently been introduced to the new curriculum (which is great by the way).
My feedback is related to the amount of sections, sub-sections and challenges that are now visible on the curriculum page.
When working through challenges, leaving them and then coming back to try and pick up where you left off, can be a bit unnecessarily tedious. Unlike the individual challenges, a user cannot see when a sub-section (or even section) is fully complete.
I suggest that, like the challenges, there is a circle next to the sub-sections and main sections which can be marked as completed or not to remind the user if completed or not.
It is a minor change which I think would help the user experience and increase productivity.
p.s hope this is the correct place for the post