This application has very convenient User Interface. Its very easy to add or modify a new weapon profile, based on a bullet from the extensive library thats included - or your own. It allows adding banded/steped BC (G1 and G7). And it works on iOS 4 and iOS 5!
One shortcoming - you cannot add a projectile to the library to then include in multiple weapon profiles. But (a) its not a big deal - it simply forces you to manually add bullet parameters to each new weapon profile, and (b) the author said hell include this feature in one of the future releases.
Accuracy-wise - Bullet Flight is probably the most accurate ballistic calculator. Its output is within what JBM and Ballistic FTE tell. When compared throughout the range (from 500m to 2000m) Bullet Flight and JBM were within 0.1-0.4mil of each other.
Did I say it has the most convenient interface? It also has a great support - usually I get replies within 24 hours from emailing questions.
Ballistic FTE is richer in features - such as drawing graphs to compare ballistics of multiple loads & projectiles. Bullet Flight is great for pure shooting - get in the field, get the weather, lase the distance (or mil the target), plug in the data, adjust and shoot.
Its the costliest - but money very well-spent. IMHO - Must-Have!