Of course it's a stupid way to get a light meter, if that's the sole reason you're getting it. But if you've already got an iPhone (I don't know if there is a similar app for Android or Blackberry), then it would be stupid NOT to get the app, because you're almost always going to be carrying the phone with you, even if you forget your handheld meter. I've used the app and it is an excellent general purpose meter, and the way it works is equivalent to about a 5-degree spot meter. So you can do highlight and shadow metering to calculate the contrast range in a scene. Of course it isn't as good at that as my Minolta Spotmeter F, but that's horses for courses. The Spotmeter F (or the Sekonic 408) does me no good if they're at home or the battery is dead.