Recently, I finished all five levels of Rosetta Stone and, while I did, indeed, learn a lot, those five levels were spread over a full year of learning.
I realized, when I would go back to spot check myself with particular lessons in a level, that there were many words that were not included in the end of lesson reviews or "milestones."
Im enjoying having this app to review and refresh my memory and, moreover, I am seeing words and expressions that I dont recall seeing in Rosetta Stone at all.
So, as a vocabulary building device, I have found this app very helpful. The prompts used, the automatic return to words misidentified, and the repetitive structure have all been surprisingly effective and useful. Probably not great for the fluent speaker, but I am intermediate, at best, and rather pleased.