In theory it's great, but the Ninth Circuit eventually overrides the will of the people.
The Ninth Circuit has no power to rule a California Constitutional Amendment unconstitutional unless they find a mechanism in the US Constitutiion which permits the federal government to disarm people.
There is no such clause, and in fact the Second Amendment is a prohibition against such a ruling. The Ninth doesn't stand a chance of affecting this amendment. There might be an attempt to continue regulating arms using the power to "regulate" interstate commerce, but Alito and others will overrule them. Even in that case, the commerce clause only protects federal laws, not California state laws.