I've never lived on halls, and it hasn't come up in conversation in a few years now, so info might be pretty outdated, but here goes.
In general the 'older' halls in what they call now the 'Residential Village' (Deakin, Farrer, Howitt, Richo, Roberts) do have fairly dated facilities, but a fairly strong social side. Obviously they do differ a bit, both in terms of amenities/facilities and culture. The newer halls ('Clayton Urban Community') are much nicer, but the social side might vary.
The halls aren't cheap (though not prohibitively expensive either, *looks at Melbourne*), and I'm pretty sure that you could save close to $100 a week by going into a sharehouse not far from campus. In general, people go to halls to meet people, but a lot do move out after first year.
Personally, I would lean towards living on campus, but really ask around as much as you can - I don't think there's anyone active here who's lived on campus.