It is good for several things even without using the superlaser. First, it will bring planets under control. Planets in the same sector as the Death Star will become more loyal to you, presumably out of fear of the Death Star. If the Death Star leaves the sector, the systems will lose loyalty to you. Also, the Death Star is great in orbital battles. At the start of the battle, the Death Star's superlaser is fully charged. So you can click on the superlaser, then a Rebel capital ship, and the Death Star will instantly destroy it. If the battle is a longer one, the superlaser will eventually recharge, allowing you to fire at another capital ship. Thirdly, the Death Star has awesome carrying capabilities in regards to fighters and troops. Also, the Death Star helps out in bombardments. When you perform a bombardment with a fleet containing a Death Star, the Death Star will increase the bombardment value, resulting in greater devastation. However, I think you have to have at least another capital ship in the fleet in order for the bombardment option to come up. The Death Star also makes good bait. Rebels will constantly be trying to sabotage it, so as long as you have plenty of troops and some good personnel in command, you should be capturing a good number of Rebel scum. Of course there's the superlaser itself, in all its planet-busting awesomeness. Sure, some people will be sad and upset when you blow away their neighbors, but so what? You just blew up a freakin' planet!!! Its an awesome way to destroy the Rebel HQ once you find it. And remember, when you blow away a planet, there is a good chance of capturing or killing the Rebel personnel on there. Lastly, the Death Star is just so cool. How can you not make one?!