Personally I think this is a good app because its simple yet affective except you can already see your battery percentage if you go onto Settings/Usage/Turn on Battery Percentage and there you have it.
But if you are on an iPod then this app is useful because you cant already show it via Settings/Usage/... .
So I do think this app is useful if you are on an iPod.
Plus this app uses up less space than the other apps similar to this one.
Overall good app!
I hope my review was helpful!
SamSalamiMan about Battery Life FREE, v3.6.12