Okay so far...

Watched 10 videos. App crashes when switching to the next video 80% of the time. Very basic narration with some corny humor thrown in. Good for beginners. Sometimes a little too repetitive or unnecessary narration.
Fix the crashes for another star.
The instability makes me apprehensive to buy other Mahalo apps like Learn Guitar. (Which you have to buy, then purchase more in-app.)

Drang about Learn GarageBand in 30 Days