Recs.
Updated
Yousician is your personal music teacher and the easiest way to learn to play a musical instrument. Yousician guides your with easy step-by-step tutorials and gives you exercises that fit your level. You get instant feedback on your accuracy and rhythm as you play along with interactive tutorials. You will see how you improve from the very first session and store your musical achievements.
SpecsUpdate
Pros
Pro Mission based gameplay with tutorials in between
Progression through Yousician is based on undertaking missions. As you learn and progress, you'll be prompted with more and more complex and difficult missions and songs. Luckily, when introducing new concepts, Yousician has a number of filmed tutorials to help better explain the new concepts and techniques.
Pro You can use your own songs
Yousician supports importing GuitarPro or MusicXML files for you to play within the app. Your songs can also be uploaded to Yousician's song database for others to play, and you can download songs others have written or transcribed.
This feature, however, is locked behind the premium version.
Pro Karaoke style playing
Yousician's interface is super simple to use and understand. A staff moves from right to left, displaying the notes you're supposed to play. As they cross over a bar in the middle, a white dot bounces from note to note, showing where you are and what you need to play next. If you're familiar with Guitar Hero, you'll be right at home.
You can see it in action here.
Cons
Con Free version is quite limited
As with many freemium software you are quite limited of what you can do until you pay.
Still you get limited time a day with all features unlocked. After that feedback feature and unlocking of new content is not available for 12 hours when the timer resets.
Ads are restricted to promotion of Premium tier, so you won't be seeing ads pestering you to download some random app.