I think the best thing about Macquarie is it's location. It is close to a train station, and it was around half an hour to the city centre. It is located in a lush suburb with a world class mall close by. Overall, I really enjoyed my experience at Mac. However there are some changes to the campus and to Macquarie station I will get into below, that you should keep in mind.
Academics were very challenging compared to back home in Canada. If you are choosing to do hard classes on your exchange I would not recommend it, instead try to pick easier ones. Professors were generally fairly good. The fact that most of the classes can be found online is very helpful, and means you do not have to show up for class.
I stayed in Dunmore Lang college. It's great if you want to stay on campus and be close to your classes. There are opportunities to party and make friends, and food is provided. However it is really expensive. I would say try to find off campus accommodation if you can. If you are really interested in socializing, Robert Menzies, Dunmore Lang, or the Village are the three options. The Village is cheaper, but it is further away and you are basically left to your own devices. I would suggest finding an off campus place close to the city, or close to one of the beaches. Since everything is online, you rarely have to come to class.
In terms of socializing, I found International students to be the most friendly and eager to make friends. The Aussie's, while nice, were a bit cliquey and hard to get to know if you do not fit their super friendly and outgoing stereotype.
However, I have heard that since I left in 2017, the campus has undergone some major changes. Trees have been uprooted at the central hub building demolished, to make room for student housing. There is also major work going on with the train station. I would look into these issues before deciding to come here, as the transit could be a major pain, and I have heard from other students that the campus is a lot worse with the renovations going on. I have no idea of the current status of these in 2019, so please look into them.
Sydney itself is a world class city and that's the main reason I suggest that you come here. There are famous landmarks such as the Opera house and Harbour Bridge, you can see every weekend. There are amazing beaches such as Bondi and Manly. The ferry rides are simply stunning and affordable. There are tons of amazing walks that you can do along the coast. The weather and water and amazing. Take easy classes, because you want to be out seeing all that Sydney has to offer. Keep in mind though it is very expensive here, and the nightlife in the actual downtown core is poor due to various laws and restrictions.