The ZAGG Invisible shield is a very important product and is used to protect your
IPhone 4 screen from scratches and breaking just like the iphone 4 cases. If you have seen the product on yahoo videos then you have seen many videos with people dropping bowling balls on the phone, placing multiple heavy items on the phone, trying to break the screen with a key as well as many other videos. Scratching the protective cover when on the phone is pretty damn hard and shouldn't with too much ease. The screen shouldn't flake back at the corners and should stay on the phone for a good amount of time. The installation of the screen protector shouldn't take too long with around 30 minutes being quoted by most people.
With the installation videos watch away you can't run into issues. ZAGG provide an instructional video for you to watch so that you won't have any problems when installing the shield. However, patience is definitely needed and clean hands will aid you. Any dirt, or dust that are on your hands will end up on the film and thus on your screen. I'm pretty sure no one wants this.
Iphones cost so much money these days is there any way you can't protect your IPhone 4. If you want extra cover then you should certainly buy a case for the phone which won't cost that much (around $20 for a good one). This will help with accidents of the phone which from my experience is very common.
In conclusion, the shield is very worthwhile and I absolutely recommend it to everyone to get for their Iphone 4 as when your screen is damaged it is forever. So do yourself a favour and buy one of these now.