Yes, at first its a lot of bleeding. Quite heavy in gushes like the others have said. I use Depends disposable underwear for the first 2-3 days of it, makes life a lot easier and no undies get ruined, everything is self contained.
The way my mw explained it is that there is an open wound in your uterus from where the placenta detaches. This has to heal, as well as the lining that built up for the whole 10 months has to come out. So, you're really supposed to take it as easy as possible (no walking/running around for a few days) to let everything heal up.
I think with DD I bled heavy straight for 2 weeks, and then from there it was like, normal period blood for another week or so, and then spotting for a few more days. I know it was a long time! Longer than I thought it would be.
One of my good friends told me too that something she didn't know ahead of time is that you still bleed heavy like this even if you have a c-section. I never new/though about that, and figured I'd pass it along!