I had a builders labourer put the pink batts in. He didn't do a great job, for example my old house has sarking and wallpaper in clumps and instead of cleaning it out and laying the insulation properly he just went over it, leaving heat to escape. I'm going to do a few session of a couple of hours each to tidy up the insulation, but it's already made a big difference. Gap in insulation really do waste a lot of heat.
If you have downlights then insulation is almost a waste of time. In the trade they're called "chimneys", as all the heat goes straight up them. According to consumer if you have one downlight, even a sealed downlight, you need to put 89% more heat into the room to keep it warm, and four downlights means you need to put in 184% more heat - ie your heating bill almost TRIPLES. I took my downlights out and replace them with standard lights on the ceiling, it made a difference, and they look good.