Do you have a phone or tablet computer? Do your kids sometimes play with it? Do you sometimes put it into your pocket, or use it without washing your hands first? If you answered yes to any of these questions, you probably should have a screen protector. A good device screen protector will be unobtrusive, securely attached, and will shield the screen of your device from any and all scratches and marks caused by rough handling, abrasions, or accidents. I have a friend who left his iPad upside down on his coffee table...picked it up, and I guess there was some dirt or dust on the table, now his iPad screen has a scratch from top to bottom. Yikes!
I have used cheap screen protectors, and don't recommend them. They tend to come unstuck at the edges, allowing dust underneath, and are stiff and hard to install without bubbles. Zagg InvisibleShields however are super flexible, stick tight and don't come undone, and although they are not super easy to install, once you do it, you'll never have to think about it again. The hardest part of the installation is the emotional leap of faith you need to make, as the process involves spraying the back of the screen protector with what I suspect to be distiller water (it comes in a little spray applicator with the shield) and then putting this WET thing onto your phone. They do advise you to remove the device battery before putting on the protector and to leave it turned off for 24 hrs afterwards - just in case - but in the case of my iPhone and iPad, the batteries aren't exactly easy to take out, so I just left them turned off for the procedure. Basically all you do is clean the screen, wet the back of the protector, place it, then use the included squeegee to push the water out and make a good tight seal between the protector and the device. Use a paper towel to catch the water as it is squished out the edges, and you should be just fine to use the device when you are done. (Note, I am not responsible for any wrecked devices resulting from following my advice!)
Zagg makes screen protectors for just about any device with a screen (I even got one for the new iPod Nano that I gave my mom as a gift last year!) so you have no excuse to not get one. They also make a ton of other products, including full body decorative and protective skins, which I may cover in a future review. Check out the selection on their website at http://www.zagg.com and be sure to follow them on Twitter and Like them on Facebook because they often have discount codes. They are not the cheapest, but considering what you'd pay to replace your device, they are so worth it.