When studying with Rosetta Stone, you basically see images and choose out of some the one that shows what's being said, or vice-versa.
Another nice feature is training your speaking abilities using voice recognition. Apart from getting you better at speaking, it can also stop you from becoming a image-clicking machine, which would otherwise be pretty likely if you tend to be inattentive.
And because everybody, including me, is lazy nowadays, ill just list the pros and cons:
- You get a feeling for the structure of the language, what goes where in a sentence, stuff like that.
- No need for studying grammar and remembering things, it's basically work-less learning.
- Sometimes, the lack of any documentation or explanation whatsoever leaves you not understanding anything anymore, but a quick Google search should be able to fix that as well.
- The speed you're teached not only to speak at but also to listen to. I can understand that beginners cant speak as fast as natives at their first time, but seriously? Its waaay to slow.
While Rosetta Stone may have some weak spots, I'd still consider it a good way to start learning Japanese.
Getting to know the basic system of a language is always good, and your speaking abilities improve as well.