I remember once hearing a linguist assert that in order to speak another language well enough to get by, one only needs to learn about one-hundred and fifty words. It's not surprising if you think about it; there are technically only seven notes in music but an endless number of songs have been created with these seven bedrock notes. Learn your "Who?" "What?" "How much?" and "When?" questions and you can navigate a foreign country well enough to get by.
But that's not really speaking; that's parroting. And speaking alone doesn't really mean that you understand the language, its rules or grammar or idioms. A lot of native English speakers, for instance, don't understand the rules of English grammar, explicitly; they've just been doing it since birth and so know instinctively when something sounds right or wrong. Learning a language from scratch as an adult when our brains are already formed means we don't have the advantages of a child born to a language, so to speak.
"Easy Step-by-Step Spanish" is a book that understands the difference between speaking a language and understanding it, and it does a good job of both teaching basic vocabulary and explaining the way cases and tenses operate in Spanish. It's not as hard as German, I've found, but it is harder than some people seem to suggest with the sort of patronizing way they dismiss Spanish as easy (I don't think it is).
The book's exercises, short readings, and graduated approach might require more time and effort than something like Rosetta Stone, but it's a better method, in my opinion. It's also much more cost-effective, which no doubt matters quite a bit to the cash-strapped student or immigrant.
I'm far from fluent in Spanish after having worked on this book, one exercise per day, over the course of ten months. But fluency usually requires immersion in the foreign country or at least being surrounded by people constantly speaking the language, and to expect to be crafting Federico Garcia Lorca-caliber poetry after a beginner book like this would be ridiculous. But by doing "Easy Spanish's" exercises repeatedly and supplementing that with watching videos on YouTube each day, I'm getting closer to my goal of fluency. And that's well worth $7.99.
I'd wish you luck in your own efforts with the book, but, as world-champion boxer Canelo Alvarez once said, "Suerte es para los mediocres." Highest recommendation.