At the moment, I do not think this is worth the money at all!! Maybe it will improve over time but right now it is pretty poor.
In the smart search it is missing many distinguishing features - like the color on the throat, etc. Even the search by name is either very weak or very incomplete.
For example, I wanted to see a list of all the hummingbirds that have a red throat -- of which there are quite a few. Nothing came up searching on hummingbird or even on a few hummingbirds by name. For instance searching for Rufous brings up only a Rufous-capped warbler; no hummingbird.
Some people claim they can leave their bird books at home and only use this app. I doubt it!
somecrazynickname about The Sibley eGuide, v1.8