I've used the app on my IPhone 4 for a couple years, mostly to support 6.8 SPC and .308 rifles. I found the data to be "spot on" for where I tested it: 25, 50, 75, and 100 yards. This is based on POIs compared to where the app said they should be for a 100 yard zero.
Until recently, I've not had a range long enough to stretch it out beyond that. I am currently in surge mode at work until 1 Oct, and hope to hit the range a bunch after that where I'll begin looking at the app info out to 200 yards on those calibers.
For what it is, I've found it to be a great tool and very informative on other calibers as well with their velocity and energy charts.