The House of the Dead: Overkill - Extended Cut allows you to play with either the PS Move or the controller, but the PS Move works considerably better than a standard controller. Even better, yet, is the Sharp Shooter, if you have one. If not, however, you can make do without.
When you have more than one player, both reticules will appear on the screen, so it works to have one person cover the left and one the right. If you are playing with a controller, you'll control your reticule with the Left Analog Stick and shoot by pressing (X), while reload is done with the (Square) button. If you are using the Move, you'll shoot with the Trigger and waggle the Move to move about, while you'll reload with the squiggle button in the center of the Move. If you are using the Sharp Shooter with the Move, you can place your hand under the gun to steady it, making your shots line up a little bit better.
As you go through the various levels, there will be objects scattered about that you can shoot, such as the red molecule looking object that turns on Slo-Mo-Fo, which makes everything slow down to a crawl to help with head shots, etc. You can also unlock concept art, 3D models, audio tracks and more by shooting the appropriate model in-game. Lastly, you can shoot money and ammo to add to your stockpile of each. You can carry two guns at a time and, since reloading can take some time, it helps to be able to hit the (Triangle) button to jump to another weapon if you are bombarded.
Upon completion of the game, you can unlock the Director's Cut which, from what I can tell, has some different angles and a bit of extra stuff to do in each level; things like dropping to the floor and having to shoot zombies as they crawl towards you. Just like in the Director's Cut of a film, it's all about the camera angles.
If you like rail shooters and are looking for a completely wrong and unapologetically rude game done in Grindhouse style, The House of the Dead: Overkill - Extended Cut would be a perfect rental for you. I can't see anyone going back to this game over and over, simply because the gameplay gets old, but it would be a fun weekend romp for two people who like rail shooters and aren't easily offended.