As best I recall, you need to be at a computer to use RS. I like to learn something while I drive to/from work, so I got Pimsleur, which is entirely audio. I've been quite happy with how it's taken my Spanish from absolute zero to usable in a lot of practical situations. (I was in Chile earlier this year, most of that time in fairly remote parts of Patagonia where English isn't of much use, so I'm not just extrapolating from how well I do with lesson responses.)