I think anyone who's used both the ZAGG invisibleSHIELD and Power Support's Crystal Film
Powersupport Combo Film Set for iPhone 4G 60-102123101 is going to prefer the latter to a wide degree -- it's just no competition.
I've had the PS Crystal Film on every iPhone since the first one and they're great. They improve the feel of using the touch screen (they make it a bit slipperier than the glass) and they don't interfere with the look (the anti-glare ones may -- I just use the regular film). They are not as a general matter "easy" to apply, but compared to ZAGG they're a cinch. And moreover, once they're on the phone, they are invisible and NEVER move.
The only reason I went with ZAGG this time is because PS didn't have films ready on iPhone launch day -- no idea why, but pretty strange. ZAGG did and I give them credit for that. BUT --
1) Installation
The ZAGG installation procedure is comically complex. It has a squirt bottle of water and a squeegee, people. Remember paying hundreds of dollars for this phone? And now you want me to SPRAY IT?
OK, fine, I'll spray it. I'll spray it and I'll squeegee it. I will be frightened but I will do it. But oh god, now that I've done it, you say I need to LEAVE THE PHONE ALONE FOR 24 HOURS? Are you *kidding*??? I just bought this! I want to play with it!
OK fine... I'll leave it for 24 hours... because you said if I didn't, the screen will peel off. So I left my beautiful new phone, on launch day, alone for 24 hours. I had to beg the AT&T guy not to shut off my old phone so that I could literally wait for ZAGG to dry. I waited 24 hours and put it in my pocket and... the front top right corner immediately peeled back. Oh hell no. I did the spray. I did the squeegee. I did the wait 24 hours. AND FAIL.
PS Crystal Film installation, by contrast? Similarly annoying to ZAGG in that they both want a dust free room (um, where?) but you literally just take the film out of the box, use the included sticky sheet to pull off the dust, carefully place on the PS film, and it's done. Immediately. No spray. No squeegee. No 24 hours. And it will never come off accidentally.
2) Look
As many others have posted, this is some kind of crazy rubbery plasticky business. It does not look good. I don't care what the other posters said about leaving it for 24 hours, or 48 hours, or a million hours. It still is a weird rubbery thing and even if you have managed to get all the air out, and even if you let it dry, there is a weird rippling/rainbow effect as you tilt the phone around. You will always notice it, and it will annoy you. It is because it is rubbery and can stretch or change thickness.
Moreover, when that corner comes up, it never really goes back down. I had people look at the phone and go "Um, what is up with that corner?" because it looks terrible. My sole goal at that point was keeping the film pressed down repeatedly to avoid scratching the glass until the PS film came.
Not to mention, self-healing? Survey says no. I ran my fingernails down the front of the screen as a test and it left scratches. They never "healed." They were always scratches, and they were always visible. Just using my fingernails.
PS film, by contrast: looks fabulous. Never peels up. No rainbow or warping effect because it is plastic and does not shift or bend. But -- it will also show scratches if you go at it.
3) Feel
The feel in your hand of the back of the phone and the sides of the phone when equipped with ZAGG is pretty pleasant, and that's why I give it two stars. The rubber does make it more grippable and you feel more secure holding it. HOWEVER...
The feel on the front of the screen is awful. Any time you're playing a game that requires quick swipes or any kind of detailed movement -- you will fail. It makes the resistance significantly more so. It is unpleasant.
And that nice rubbery texture when you're holding the phone? If you put it down on any surface - glass, polished wood, leather car seats -- it STICKS. It sticks to the point where it makes a sound when you lift it up. It sticks to the point where sometimes the film gets lifted up by whatever you put the phone on. I've had it happen with laminated ID cards in my wallet, with car seats, with my glass coffee table, etc. Not good.
PS, by contrast? Feels amazing. It feels better than the glass. It is so easy to work with the touch screen that it makes the iPhone better. It does not, however, help you grip -- and even the dual film package won't protect the sides.
Conclusion -- do not buy the ZAGG. The only part of the ZAGG I've left on is the back and the sides. The back hasn't peeled up yet in a way that makes it terrible, but I assume it will happen inevitably. Until then, I'll leave it to protect the back and I'll just be annoyed that it sticks to everything. The sides have been fine and I assume will protect the corners a bit. But the front -- oh, the front ZAGG came off the second PS came in the house and I've not looked back. Go Power Support.