Hi,
I am in my third year of this degree - it's been great and I highly recommend it, great lecturers, facilities, units and resources.
Exams - whether or not you have exams depends entirely on the lecturer who delivers the course and their assessment preferences. Generally speaking though, yes there will be exams (I've always had at least three per semester). Take-home exams are also quite common in the social sciences, so you get say two essay questions that you complete within maybe 4-5 days (obviously referencing/research requirements are not quite as high). Mid-semester exams are pretty rare, although you might get the occasional 'quiz' worth up to 20%. In my experience, you can generally expect to complete four assessments for each unit - an exam of sorts, tutorial participation, a major research essay and a shorter research essay/review/presentation.
I am doing a major in Political Economy - which I have really enjoyed (I've only really struggled with one unit), I've also done a fair bit of Anth and Govt which complemented my major well. Political economy is essentially heterodox economics with an international focus, taught from a social sciences perspective, meaning much more of a focus on critically analysing the mainstream as well as the philosophy of economics, as in what it is trying to achieve and the implications. There are general core units you take to do a major and they focus on the international economic system, history of economic theory and economic policy. Plus quite an array of electives covering everything from economic data analysis (if you want some practical skills), to human rights and development.
Is economics hard? Well that depends on your interests, your skills and how well you want to do. Most subjects are hard when it's HDs you're aiming for. Content wise, mainstream economics based on a mathematical/quantitative framework so you will need to be relatively on top of your maths. If you're more so of a humanities/english background then political economy may be the way to go, because there is some content cross-over, but it is delivered very differently. In political economy, you still get all the maths/graphs/equations that you do in economics, but you also get an explanation in words.
I'm gonna go for the sell here and say Sydney is the only uni in Aus where you can do political economy and you will be exposed to world class scholars. Employment wise, political economy is a fantastic accomplice to straight economics as it gives you the breadth, while economics focuses you the depth (we have had RBA reps come and speak to us about graduate positions).
Is there anything else you'd like to know about the course?