My experience, it's a "hard" subject depending on what you compare it to you and the skills. If you have a decent memory and decent essay writing skills, it should present no troubles as a subject. It is a much harder subject than business (although that sub just seems common sense to me because my family run businesses).
I did extremely well in Yr 9/10 commerce (99% every semester yr 9 and 10 lol) and I'd say there is little eco content in it, more geared towards legal and business. But if you do really well in commerce you probably have the brain so to speak to pick up economics easily.
So moral of the story is, if you are great at commerce, have an interest in eco and don't slack off like I did, it will be a great subject for you. But I feel it is one of those subjects where the teacher can make a huge difference.
In Yr 11, I found it easy at first (first test or two were pieces of cake) but we didn't have a good teacher, he spent most of the time just talking about non school things (hiliarious, but not good for school). We had not much notes, but I didn't study very much at all for the yearlies (night before FTW) and still cleaned up 2nd overall in eco. I would say it's a good subject. At the start of Yr 12 I agonized over dropping it because the teacher who takes it in Yr 12 is absolutely amazing, and apparently now it is some of my friends favourite subject. They get a lot of work done now and it's very structured. I dropped it because of a sheer units thing (wanting to try his ext and ee2), that other subbies that I probs performed worse in would be useful for uni as I am going to study science and I suppose it was soured a lil in my mind from the agonizing prelim year, I found it a bit dry. But considering the natural ability and results I had in it and its lovely scaling, it probably would have been a safer bet for me if I had kept it. But that is hard to speculate as the eco cohort was smaller than my other subs and lawl, half the class dropped out when I did.