I used Rosetta Stone softwrare in my TOEFL class and I wrote a MA thesis about the experience. Basically, I found an astounding lack of interest in the software. RS has a speaking exercise where students try to emulate the pronuncation of the native English speaker. On paper, it sounds good, but in practice, I found that students didn't care for it.

The students liked getting instant feedback on the reading and listening exercises, but that was like educational Playstation for them.

The writing exercise challenged them, because they had to realize that English has very little sound/symbol correlation.

Overall, interest in it was 3 on a scale of 1-10.

C'est la vie!