Ok I really wanted to like this, but it has flaws. To hold the sharpshooter you should really be standing with the stock against your shoulder. This was surprisingly uncomfortable, and more importantly, holding it with any sort of pressure against the shoulder risks activating the "Pump" action at the front of the gun. I found myself cursing several times at unintentional firings of the pump action. The "Pump" needs a lock or some serious resistance so you won't set it off unless you mean it. It's a design flaw IMHO, as is the stock which can't be removed.
So, resigned to sitting on the couch with the gun by my side, I went about playing the Killzone 3 demo. Turning was the main challenge, and took much practice and calibration in the settings. After hours of playing and calibrating to my liking I was doing nearly as well as with the Dualshock, but having more fun. That said, I was also getting sore in my left arm for extending it for so long and my right hand needed five minutes of flexing as a break.
Other problems were I couldn't reload very easily by rotating the gun, though I hear the full game uses the pump action to reload, and that would be fine (unless you accidentally set off the pump of course.)
The 'melee by stabbing' motion was hard to pull off, and would sometimes turn me around if I didn't connect with an enemy, which meant I would die a second later. I attribute this to the unwieldy nature of using a gun peripheral in this manner.
The jump button has been remapped for Killzone 3 from X to the square beside the trigger. This was wisely done so you can use the Nav. stick to move and still have a button to press for jumping. Unfortunately this means I would need to take my finger off the trigger to jump and then put it back, which is harder than it sounds, or use the middle finger for trigger as my index presses buttons. Neither is ideal, and I like to jump a lot in my FPS.
Lastly, the fact that the move controller is not in my hand but on the end of the gun-barrel changes the way the move reacts in game. I didn't realize how much of a difference until, in semi-frustration, I removed the move controllers from the sharpshooter and played with move control alone. It was a revelation. Everything I mentioned, reloading, melee, jumping, all solved. Buttons were all easy to reach. Movements, response, and turning were not just manageable but better than dualshock! In fact I dominated the Killzone demo so well that I will never go back to dualshock, or the sharpshooter for that matter. Good job, Sony, for making the Move controller work so perfectly. Oh, and it was comfortable; I could have played with the move alone all day.
***Positives: Feels like you're pointing a gun. Fun for light FPS campaign and rail-shooters. Digital trigger and remapped buttons are real deal!
Will not improve your game as I had originally thought.
"Pump" action far to easy to activate accidentally.
Stock is uncomfortable, unwieldy when not used, and cannot be removed.
Tiring. Might make you sore after long excursions.
NOT GOOD in online multiplayer (use regular Move here).
Aggravating placement of some buttons compared to using the Move "wand" by itself.
Melee 'stabbing' motions are jarring at best and possibly dangerous to perform.
***Conclusion: Fun alternative if you're not serious about dominating your game. Some flaws could be addressed in a second edition. Move controller is far superior by itself, but doesn't feel like a gun of course.
If you're interested in getting the most out of your move in Killzone, google "iwaggle killzone 3."