This has got to be, hands down, one of my favorite bird song and call identification apps. I like the option to create your own study lists based on family, region or season, as well as the freedom to create study lists that do not necessarily reflect the aforementioned groupings.
Although there are no notes regarding the songs and calls, it makes me focus and listen more intently to each sound to pick up on elements such as repetition, rhythm and rests, but also to pick up on general sound features of each bird family, because there are quite a few secondary bird sounds that sound superficially similar to birds outside the family. Having said that, this app may appeal to birders who are already familiar with some or most of the birds included, so it would be utilized as something of a refresher course or supplement to existing knowledge.
My only issue is not having variations of birds that are widespread across the U.S. since one species can sound distinct in another part of the country while still retaining the same overall "feel" of a song.
It would be great if this app addressed this with downloadable song packs directly from the app to address this or include additional groups such as raptors, waterfowl and commonly seen shorebirds.
Aside from that, I am pleased with the number of bird species and sounds already included. The fact that it's linked to Game Center is only icing on the cake.