I am always on the hunt for the smallest, most useful, most full featured items to carry with me and if I can drop an item out of my EDC, I am thrilled to do it. I am not a person that believes in carrying a backpack full of gear on an everyday basis. So I thought I'd see what would happen if I dropped a flashlight from my daily carry. I wasn't seriously considering this as a long term plan, but just an experiment--I like flashlights too much to leave them at home permanently. Think of how sad my Spy 007 would get, just sitting there on my shelf all day.
I carried just an iPhone as my flashlight for about five days, two of which were consecutive, and here is what I found.
First, the tint on the light is quite good, better, for example than the tint on stock 47s cool emitters. There is very little in the way of purple or blue or green. This is probably due to the fact that it needs to be able to take relatively lifelike pictures.
Second, I have to commend Apple for a great interface--the ability to access the light on the slide up menu is awesome. It is easy to use and intuitively place, exactly like Apple products should be. It also blows away the fiddly apps out there that just never seem to work right.
Third, I really did try to like the flashlight feature. I hoped that I would be persuaded enough to occasionally leave a light at home even if it didn't replace the lights entirely.
But there are few problems with the iPhone flashlight that convinced me that it was not a replacement for a standalone light.
The iPhone itself is an awfully expensive piece of equipment. Out of contract replacement costs start at $600. That is more expensive than all but one of my flashlights and I have a pretty darn nice flashlight collection. So the idea that you would want to use your iPhone as a flashlight instead of a $60 Zebralight doesn't make a whole lot of financial sense, especially when you consider that at least some of your flashlight use will occur in adverse conditions (down in a basement with a water leak, outside in the cold and dark, etc.).
Additionally the shape of the iPhone does not make it easy to use. Holding a slick, thin, wide device is awesome for talking and browsing the web, but when you need to point your iPhone light at something it can be quite awkward, bringing to my its replacement cost. Additionally, many times I use my light in my teeth, doing handsfree work. This is impossible with an iPhone.
Then there are the limitations of the emitter itself. First, it has no reflector at all. This means you cannot get a focused beam and a ceiling bounce is impossible. Second, its not all that bright. Essentially the iPhone flashlight is as bright as an LRI Photon. In fact, the iPhone light is almost a perfect replica, in performance terms, to the Photon. Its great at illuminating doorknob in front of you (though the grip problems make this unadvisable), but forget about checking around your yard for bumps in the night.
In short, the iPhone light is not good enough, even though it is essentially free (in terms of space, additional cost, and batteries) to make it worth not carrying a good, compact modern standalone light. If you carry nothing, its a good feature. I'd probably never buy a Photon style light if I owned a smartphone with a light feature, though I have a special hatred for button cell lights.
The iPhone light is basically the equivalent of keys for people that use their keys to open packages--it sometimes, under perfect circumstances, can do okay. If that limited use profile is good for you, then you probably aren't a regular reader of this site. Furthermore, with the improvement in emitter technology over the past five years, the size and capabilities of standalone lights has improved so much. Your not lugging around your Surefire 6P anymore. Its probably something with a single cell that is no bigger than your index finger. And given that competition, the iPhone light stands no chance.