OK Mitch...
I have to get this off my chest. iBirdPlus has made life worth living. Ok, maybe that's a bit much, but I cannot tell you how much I use and love this program!
I have a place in the Piney Woods of East Texas (on Lake Livingston.) We are lucky to enjoy one of the areas in the US to be able to see the most diverse selection of North American birds. I literally live on my iPhone as I watch the various residents and migrants that pass through my backyard. While I still keep my field guides handy, IBirdPlus has made identifying the newbies much easier.
As a testament to the recorded calls, I have even had an Arcadian Flycatcher come down to greet me when I played that call while playing with the program. I had never seen one here before. (NOTE: I now only play back bird songs indoors so as not to disrupt natural behaviors.)
As an early tech adopter, I am anxious to try iBirdPro. The "search by call" feature I've read about is all-to-enticing. But I may wait until Apple has sorted out the upgrade issues as suggested in previous posts.
Thank you again for such a wonderful program - you all are helping the birding community immensely!