Common stereotype i',m afraid. It's like any other city, it can be boring, it can be exciting, it's what you make of it. It has loads of cultural events on most weekends and during the week, a vibrant theatre scene etc etc. No offense, but in my experience people who find places like Canberra boring are the same ones that either (a) also find places like NY boring or (b) think a great night out consists of getting blind drunk and eating curry at 6am in the morning.
It's just my opinion, if you want to believe a stereotype i won't stop you

I thought Canberra was REAL boring...
I've had a few friends there, and they're complaining to me day n night how lifeless that place is. I've thought of going over there to work too... and feedback from residents there are like: "Go to a city instead. There's nothing here." great place for seniors and retirees only. what an encouragement!!?