As a 4th year Music Composition Major and a vocalist, I can say that this game certainly provides a rather interesting way to improve intonation. Though it advertises as only teaching a few instruments, it will actually pick up anything that you play over a microphone.
What I will say is that the editing software is rather basic. If you want to write a decent score, then let me inform you that there are far better programs that are out there for free. However, the editing software will provide a way to upload your own compositions to the game. It's a bit clunky, and it takes a little bit to figure out exactly what the program is doing, but it does work.
Overall, I'd say this is absolutely something that an aspiring musician ought to check out, and especially so if you wish to perform on an instrument like Violin, Viola, Cello, Double Bass, Trombone, or Voice!
If you wish to see some gameplay footage, then you can watch this video that I have made here: https://www.youtube.com/watch?v=tN5MdN7JzHU
Posted: November 27th, 2013