I have this on my iPod touch. It's not bad but as you say there are only 112 birds so far. I had ispiny too and the new Bird Guide app. ispiny adds new birds about once a month. Bird guide should follow suit as it's quite pricey and add stuff to their app soon. All worth having.
I haven't bothered with this because it's obviously too limited in content (are there really no waterfowl and waders?) and the Birdguides app, while three times the price, has about 10 times the content.