I've been going through the process of learning Spanish for the past year or two (with various levels of dedication) and I have also thought about starting yet another language learning app. I used RosettaStone and DuoLingo for a while and they both provided a lot of value, but for sure the greatest benefit came from doing 1 on 1 lessons with native speakers. Lots of progress then.

One thing I've noticed with all the language learning apps though is that they are generalized methodologies that are then applied to lots of languages. IE, duolingo in French and Spanish and German are basically the same track, just in different langauges. Same with Rosetta Stone (even more consistent there).

That seems to really be leaving a lot on the table. Every language has its quirks and most importantly every language has a few shortcuts you can learn to really give yourself a ton of utility with little work. But because the software is built to be generalized you get the lowest common denominator instead of the fastest possible path to fluency and speaking.

Not sure which approach chatterbug is taking, but at first blush and by the way they talk about it I'm guessing it is yet another generalized approach, but I suppose we'll see.