Is this a gun, as in a fully functional and useful tool? No. But it's not proof of any kind that 3d guns are impractical in principle (as that Register article claims); quite the contrary. The Liberator proved that it's possible to print a gun that can be fired (unreliably) on a printer, without blowing up. The Lulz version proves it is possible to create one that can be fired repeatedly, and can be created on a consumer grade printer. From here on in the reliability will improve, and perhaps someone will come up with a double barreled one or a six-shooter even.
This development is not interesting for gun enthusiasts. It may be interesting for people who need to smuggle a gun past security (you still need to get the metal parts + cartridges through the detector). It's not that interesting for people with the skills, tools and smarts to build their own gun, nor is it for criminals who can (in most countries) quite simply acquire a gun from an illegal source. But it is very interesting for people who want to acquire a gun illegally, not necessarily because they want to use it for criminal purposes, but in case they want one to defend themselves but the gov't doesn't let them have one.
And for that purpose, you wouldn't really need something that can reliably fire 10.000 rounds. 6 reliable shots would already be a vast improvement over nothing at all. And given the progress already made on these printers, I'd say that printing and assembling such a gun by anyone may well be viable in a few years.