Now Audubon Birds is always the first birding field guide app I recommend to friends and family. It's affordable ($9.99) in comparison to the Sibley app ($19.99). Audubon Birds is the most intuitive and user-friendly of all the birding field guide apps, and it's the most aesthetically pleasing app to look at and use. The latest updates even have better diagnostic photos of the birds with helpful field marks pointed out with a simple icon tap.
I love that Audubon Birds allows you to "Find Birds with eBird" and I'm confident that it won't be long before bird sightings entered into NatureShare will also sync with eBird. Imagine the ability to enter all flora and fauna sightings into an app, that can be shared, and can contribute to science! I think NatureShare and Audubon Guides is well on their way to accomplishing this.
Here are some screen shots of the updated Audubon Birds app: