I have been using this app for a few years now. I found that it was better during its earlier versions. In its current state, the app frequently says that it’s unable to identity the bird in the audio clip. I sometimes wonder if the app creators are too strict in their regional restrictions of sources. Basically, when you use the app, it uses your location to identify what types of birds are usually found in your area. It then uses this list to compare audio captures to. The problem is, I think it cuts out a large chunk of migratory birds that may not be as common as the creators are restricting their sources to. Thus, you may only have luck identifying common birds, but at that point you probably already know what those birds are to begin with.
I find the Merlin bird identification app to be better even though it only goes by physical descriptions and not audio captures. Both are connected to Cornell’s Ornithology lab, but the Merlin app lets you choose what sources you want to utilize, and this allows you to identify those rare birds in your area.