Wow, haven't been here in a while, and then I see a whole thread devoted to my home city.
So, I'm a Montrealer and I've been to Sydney. Both awesome cities. Montreal's probably closer in feel to Melbourne than to Sydney, though. Very arts-and-cafe culture here. And no beach. Sydney has a beach. And hot weather. Very hot weather. Montreal has very cold weather. And lots of snow. And hockey, of course. So if you prefer the cold to the heat (like me), then you'll probably prefer Montreal. Just don't underestimate the brutal winters - they'll kick your ass.
Montreal's a very liberal, multicultural city. And yes, very GLBT-friendly, though nobody really makes a big deal about that anymore. It's sort of live and let live, you know? My friends are a very mixed bunch. It's been years since anyone has batted an eyelash in my circles, anyway. Yeah, there's the Village (though most of the people moving in lately are young straight couples with kids) and there's Divers/Cite and the festivals and stuff, but it's just sort of a part of the incredibly diverse fabric of the city. Summer is nonstop festivals anyway, and everyone kind of gets into the spirit of things. People are more likely to pay attention to whether you're a vegan cycling activist who eats organic than to your sexuality, whatever it may be. It's just a non-issue, unless you want it to be.
Quebecois/French is sort of like Australian English/American English. Same language, but just barely. The accents and expressions are very different. But don't worry about it too much; if you were to spend any length of time here, you'd adapt. English is widely spoken, too. And new immigrants to Quebec can get free French lessons from the government.
Is there bullshit to deal with here? Sure there is. The language politics crap crops up every once in a while, usually when politicians are trying to stir up shit for votes. The economic woes have led to a massive population migration to Toronto over the past quarter-century for jobs. If you don't speak French it can be a bit tricky to find gainful employment, though contacts help here. Our roads have potholes the size of, well, Australia, and we just re-elected a massively corrupt mayor because the other choices were even worse. Not to mention, it was minus-30 last week. So it's not paradise here, by any means.
All that being said - and I'm biased because I adore my city - but, having traveled all over the world, I really believe this is the best place in the world to live. Come visit, check it out, see what you think.
(By the way: The guys with French accents? Highly overrated. IMHO, the guys with Australian accents are much hotter. But, the grass is always greener and all that, right?)