I'm basically OK with this. My personal, layman's view has always been that both the history and the wording of the Second Amendment point toward a limited, personal right to bear arms, not merely the right for a militia to be armed. On a practical level I'm less sure whether this is a good thing, since I've never gotten into the policy weeds of handgun control and whether it's effective. Still: a right's a right. The wording of the Second Amendment suggests to me that the government can regulate guns a bit more than they can regulate, say, speech, but that they can't flatly ban them.
On another note, this is the latest in a whole bunch of high-profile 5-4 Supreme Court rulings this term. I wonder if that means that the composition of the court will be an even bigger campaign issue than it otherwise would be? My guess is yes.