I've had good luck with Pimsleur language programs, both with Italian and Spanish. I don't know how it compares vs. Rosetta Stone, but it's a pretty efficient system if you're preparing to travel somewhere and don't have a ton of time to take a conventional language course. (I've had years of formal French and Mandarin coursework, and I felt like I got comfortable with the "feel" of Italian much more quickly using the Pimsleur tapes).

The emphasis is on the vocabulary, grammar and pronunciation that you would need as a traveler, so you get drilled with greetings, how to order at a restaurant, discussing transportation, using numbers to describe things and money.

I think an advantage to using a product like Pimsleur or Rosetta is that you're not sitting in a classroom listening to your classmates struggle with pronunciation. One of the things Pimsleur emphasizes is to listen and respond to the speaker at a similar speed. Early lessons are a bit slower and simpler, but then they get progressively more complicated and speed up to a more regular pace of conversation. Two months of working with recordings and I was much more comfortable with Italian vs. seven years of French, albeit with a limited vocabulary.

Probably any system like this is no substitute for practicing conversation with native speakers, but they can help you get a good foundation with things that you would find immediately useful.