I've visited Canberra a bit, my sister did her Masters there and now works there, as I was considering going there for a little bit. Was actually just down recently in the holidays.
My friends all enjoy ANU, it's a great uni, particularly for IR or any language study (particular in the Asia-Pacific languages), also some great science/engineering programs and a very good law school and other humanities. Such a strong uni in many regards, very highly regarded obviously. Smaller undergraduate population than a lot of other major universities so it can feel less of a cattle call.
There is the first year accommodation guarantee, and my friends from the colleges to the UniLodge love campus life in that regard. If you are heavily involved in university, there will be a lot of parties and activities. Yes, the nightlife is not like Sydney's, but it tends to move people to a more house party dynamic opposed to clubbing from what I've observed. But the uni still has great events, so as a uni student it's not like you'll feel destitute at all in that pursuit
It really depends what type of dynamic in a place. You may find it a nice change from Sydney or you may find you are a super, super 'city' person that prefers Sydney. I know I chose Syd because Canberra was more closer to where I lived and I wanted a bit more of a change from where I was living. You should visit there yourself and hang around for a few days and see if it feels it suits you. Get someone that lives in Canberra to show you around as they tend to know all the nice little niches of the place. There's nice markets on the weekends and nice cafe niches.
