“Does the bill really repeal it, or does it simply reduce the penalty to zero?”
As the bill is now, it does repeal the penalties.
Everything You Need to Know About the GOP Tax Bill
Bloomberg News
December 15, 2017, 11:20 AM EST
Updated on December 15, 2017, 7:00 PM EST
https://www.bloomberg.com/news/articles/2017-12-15/everything-you-need-to-know-about-the-gop-tax-overhaul-bill
Merely 'repealing' the penalties is a dodge - a cowardly and meaningless gesture, meant to appease an angry, but ill-informed electorate.
Any future congress can raise the penalty again, unless the MANDATE itself is repealed.