I've tried screen films for both iPhone and iPad, not so much for protection, but for glare reduction and finger gook reduction.
By far, the best was the anti-glare film for iPhone 3G from
Power Support (was in the green package when the Apple Store was still selling screen protectors); they also have clear ones. It was, by far, the easiest to install, never noticed any fingerprints, finger feel was exceptional, and the artifacting from the matte screen was minimal.
Eventually, after 18 months, it started coming up at the edges due to an ill-fitting
pong research case that continually scraped the edge of the film, causing crud to build up under the edges, so i had to replace the film (I removed the case and have not replaced it).
Since I plan to get an iPhone 4, i didn't want to waste money on a film i was only going to use for a few months, so i tried the clear film that came free with my old
ifrogz case. Very decent film, although it isn't quite clear (some rainbowing if you look at it closely from the side), finger feel is acceptable, but not as good as Power Support, and the smudge protection isn't as good, but it will do for the next month.
BTW - I had the ifrogz case before the pong case - it lasted about a year but I had to replace it because the thin piece of plastic between the home button and the recharger slot cracked and eventually came off. This was probably due to stress from putting it in the dock every night for recharging. That shouldn't happen, but I would still consider them for my iPhone 4 case. The case had an excellent hand-feel and looked very nice. My wife has the crystal clear ifrogz case, loves the way it feels in her hand and has had zero problems with it (the crystal case is slightly thicker than the color cases).
On to the iPad. I'm using the
Apple case and like it primarily for the thinness. I've considered others but they all add too much bulk to it. As for screen films, I haven't had much luck.
At first, I tried the highly-regarded
ZAGG invisible shield. It was impossible for me to install properly and had really poor finger-feel (finger drags and skips across the screen), so i returned it. True to their word, they do refund the film even though I tried to use it and failed, so if you want to try it anyway (because other people seem to like it), i would still recommend them for that reason.
After that, I tried a cheap ChiTek film which went on well, but i'll replace it soon. The finger feel is acceptable, but there is a lot of rainbowing that you can see, even head-on. For $5, you can't beat it if you want a cheap film.
I've decided to replace the iPad film (and get one for my 13" MacBook) with anti-glare films from
Photodon since I had a lot of success with their anti-glare film for my wife's 20" iMac. I'll let you know how it goes.
BTW - has anyone out there used the
ZAGG smartBuds? I like the idea of the buds hanging close to my ears, even when they're out, but I have a 20" neck and it looks like it might be a tight fit.