I've used heparin many times for a patient with DIC, to help prevent microemboli. It's most definitley controversial, at least it was 3 years ago when I took several critical care courses and did a lot of reading on the subject. From my understanding, more docs opt for the Heparin than don't, though. The latest I've read is that if the underlying cause is quickly treatable, like after an amniotic fluid embolus, you should use only replacement therapy. Heparin use is controversial when there might be an unacceptable increase in bleeding, like post-op .
Prognosis depends on the underlying disease.
Meanwhile, yes, they bleed like stuck pigs. They were doing that anyway, with their clotting factors all used up on the intravascular clots.