Rosetta Stone gets a lot of publicity, perhaps because of its large marketing budget. And finding individual reviews is easy--some people love it, some hate it, some have mixed feelings.
But has any study been done on the system to determine whether it's actually effective either as the primary learning tool, or perhaps as a supplement to other learning methods?
A quick survey of literature (and I mean quick - maybe 15 minutes) suggests that RS is effective - but that effectiveness varies on a variety of factors, such as previous language experience, cultural appropriateness, etc.
This article on RS's use with ESL students in Nigeria suggests that it was highly effective at improving student's proficiency, but there were cultural shortcomings with the software.
This article on RS's use in expanding the English vocabulary of Iranian students also suggests that it was highly effective, especially due to the self-paced nature of the course.
This report on RS's use in teaching elementary-aged children in the US suggests that RS "was engaging and resulted in development in terms of measurable language learning" (Chinese & Spanish). Live tutors were noted as an important component, however.
