Appears to be a serious civil rights win

and the commissars of the People's Republic of Maryland must be crapping bricks.
In our view, Maryland law implicates the core protection of the Second Amendment—“the right of law-abiding responsible citizens to use arms in defense of hearth and home,” District of Columbia v. Heller, 554 U.S. 570, 635 (2008), and we are compelled by Heller and McDonald v. City of Chicago, 561 U.S. 742 (2010), as well as our own precedent in the wake of these decisions, to conclude that the burden is substantial and strict scrutiny is the applicable standard of review for Plaintiffs’ Second Amendment claim. Thus, the panel vacates the district court’s denial of Plaintiffs’ Second Amendment claims and remands for the district court to apply strict scrutiny. 

And Branca notes
In brief, the court’s 2-to-1 majority concluded first that the guns and magazines banned by the FSA fall within the scope of the Second Amendment, and second that:

Strict scrutiny, then, is the appropriate level of scrutiny to apply to the ban of semi- automatic rifles and magazines holding more than 10 rounds.

This appears to be pretty big.  Full article at the link includes the court opinion.