And you lose a lot of the benefits of Django, to be fair. We use Jinja2 on DrawQuest but it was a bit messy to add back features like the Django context processor.
I'd love to hear more. We are considering Django with Jinja2, primarily because I think some of the Django template opinions are a bit wrong. I don't want to fight one direction in my efforts to keep from fighting another, though. I'd prefer the details I know. :)