I have been using Ear Trainer for a while but was becoming frustrated with the fixed lesson format. It would not let me configure the intervals I needed practice on. This app lets me configure everything!
The other big item I was looking for was melody playback. This app plays a melody then lets you repeat it on an instrument of your choice. It listens through the mike and shows you what you played. This is the next best thing to having a teacher work with you.
A unique feature is the ability to add notes before or after an interval. This makes identification harder than you might think. It is a great building block for melody playback.
You can also play the second note in the interval on your instrument or an onscreen keyboard. This really helps me to find the correct range on my piano. If you are using an instrument with a smaller range, you can set it to accept the answer in any range.
This has everything I need to work on all aspects of my ear training. I love it!
I hope they use the ability to hear the instrument to make a sight reading trainer as well!
LN137 about Right Note - Ear Trainer, v1.4