Very good in some areas, but could do with improvement...
I had heard from my friends how successful Rosetta Stone is meant to be, so I myself went out and bought all Spanish levels, 1, 2 and 3, as I've been wanting to learn Spanish for quite a long time. As an already fluent speaker in both English and French, I was impressed at how easy it made vocabulary learning. However, I feel uncomfortable with all the grammatical rules and the exact meanings and contexts of certain verbs, so if there's anything that you get hung up about, I urge you to not rely on your instinct, look it up!
As for the pictures, they were often quite misleading. To cut a long story short, it only made sense once you knew the meaning of the accompanying sentence, yet it was tricky if not impossible to infer the meaning without intervention from the Internet / dictionaries etc. Rosetta Stone should by no means be used as a direct path to language fluency, it is essential that there are other sources of information used than Rosetta Stone and your own, often faltering, intuition.
About a year back, I borrowed a copy of the Japanese program from a friend who had told me it was useless. And I totally agreed with him on that. I think that in languages that are so foreign, it is a major problem for everything to be left to the intuition and, less so with help from the Internet, it's fiendishly difficult to get your head around. The only way to learn a language with absolutely no roots in Latin or Greek etc, in my estimation, is to either get a qualified tutor or to go and live in the country where the language is spoken.
To conclude, I would recommend Rosetta Stone as a means of a push in the right direction. I now speak nearly fluent Spanish and would not have been able to do so without Rosetta Stone. Remember though, if you do invest in the product, it is essential that you draw information from other sources as well.