I'm doing it at the moment. Unit three is pretty manageable. It starts with ADTs/graph theory and really simple algorithms like prim's but quickly gets challenging, you need to be paying full attention for ones like Bellerman-Ford and Floyd-warshall. The folio tasks at our school were pretty fun to do, which we did everything from making a graph of movie characters as our first one (I did mine on inglorious basterds, for example) to creating a social network graph and applying our own algorithm to it - which we needed to make.
Unit 3 is important preparation for unit 4, which I personally think is much harder, because your assessment tasks become much more like SACs. It is a lot more math heavy and sometimes difficult to grasp your head around because the content is presented to you to analyse, rather than having to create it.
I'm interested to see how the scaling goes, it's definitely a challenging subject and made especially hard from the lack of VCE-tailored resources. You find that googling a lot of key concepts leads to complicated wiki pages with lots of information outside the course, mainly because the course itself skims over a lot of topics, only diving into them on a somewhat shallow level. Still, I found loads of resources on youtube that helped me grasp concepts well, as well as the alexandria repository.
I think that with us human guinea pigs going through it the first time, there should be a lot more notes and resources by next year and I'm sure the subjects popularity will grow because of that.