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:
Pro:
- 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.
Contra:
- 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.
Conclusion:
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.