The reasons guided missile works so well as opposed to laser and railguns is both of the latter two fire straight, except they really can't because of air. Both also require massive loads of electricity which we just don't have the battery quality for yet. Lasers attenuate like crazy in air, you can fire them at high altitudes, but ground to ground (or low altitude) or anything pretty much straight down. After that your intersecting more an more air, just firing perpendicular to the earth's surface a one square in beam has to intersect 14 pounds of air, ditto a railgun bullet with a one-sq-in crossection. Unless you get much better batteries - way better than we have now - you just can't make a weapon as compact as a rocket or gunpowder driven projectile.

The things - barring massive improvements in battery technology, and I mean MASSIVE - really are only good in space, for shooting down missiles or sattelites, and then you have a problem acquiring power to run them. You need either very large solar panels or an onboard nuclear reactor, which besides violating a bunch of arms treaties has the problem with heat disspiation - you can only radiate heat in space so it has to have a large surface area that you might as well just make solar paneled. Both lasers and railguns have that limitation. On the ground or low altitude neither show a marked improvement over traditional unguided weapons, and missiles out perform them all, although ironically missile are incredibly weak against lasers - you can fry out their guidance systems easier than you can blow them up, or you can hit them during launch phase and depending on the propellant potentially set off it's fuel.

So, yeah, cool, but honestly that whole area of weapons research has been coughing up over-priced minor improvements for a couple decades now, and this test seems another example.