My advice is to shoot everything that looks breakable. You get points for damage and you might find something useful. An info screen pops up at the end of each level, giving you your score based on how many androids you dispatched, how accurate you were and how much damage you did. You get bonus points for streaks - killing a number of bad guys without missing. Graphics are clean and colorful, with excellent explosions.
Sound effects are pretty good.
There's just one problem with this game, a problem it shares with other light gun-type productions. Nothing ever changes. The same bad guys pop up at the same place, at the same time, every time you play. So running through the game a few times really decreases the fun - unless you'd rather rack up a huge score than face a new challenge. To me, the lack of change really decreases the replay value - and makes buying the game a less attractive proposition.