While not a substitute for a *good* teacher, it is a much better option than many crappy teachers, and most guitar teachers are pretty crappy. While I haven't gotten to "hero" yet, I've gone from Zero, to well, having callouses and being able to improvise over scales in a mere 30-something hours of practice with the app.
The way I've been explaining this game to my friends is, think Guitar Hero but make it an educational game with a real guitar. Individual phrases are simplified and you level them up individually from each other, and instead of "failing" you if you miss too many notes the game tries to keep you at a level to where you're on your toes.
One thing I really appreciate about this game is that it's teaching me actual songs I can relate to. I sat down the other day to practice a prhase from one of the Radiohead songs, realized it's in the same key as the primary Salsa riff, the Game of Thrones theme, the Legend of Zelda theme and the Super Mario Castle music, and had a lot of fun going between them all. I'm not just learning more about the guitar, I'm learning more about music.
One thing I find really frustrating with this game is that it has a hard time recognizing my playing of some techniques. It doesn't recognize a vast majority of my pitch bends, for example, though an accomplished guitarist friend of mine says they're fine. The game doesn't offer any feedback on how I might improve them, other than to watch the tutorial video again.
Overall, if you want to learn guitar, it's hard to go wrong with this game as part of a larger practice. Props to Ubisoft for creating something that's more about learning and less about ego.