Everybody who has been in the field of linguistics and language learning will have learned of Dr. Paul Pimsleur - one of the leading lights in the world of applied linguistics.
Dr. Pimsleur developed a system in which a student can theoretically learn a language through his program of specially formulated and designed audio lessons, which students will find will grant them a decent vocabulary and almost native pronunciation within a short period of time, albeit offering not so much in the realm of writing or reading comprehension (although the Pimsleur series includes additional coursework for this) - and to students' amazement, to be able to communicate and carry a short conversation right away.
I have used and completed this program myself not just for Italian, but also for Portuguese - with that in mind, I have first-hand experience of how it works, its pros and cons, and how useful it will be to Italian language learners. Let's go through the ways, shall we?
How Pimsleur Italian Works
The Pimsleur Italian method includes Level 1, Level 2, and Level 3 courses, all of which are interconnected and are meant to be taken from start to end. These courses are then broken down into 30-minute lessons that are meant to be taken once a day - and you are not supposed to progress any further unless you've been able to successfully hit a completion rate that is decided by how fast you can react to the course - and it is totally autodidatic. That is, you can literally teach yourself Italian within a span of weeks or months.
The Pimsleur system is well-regarded for a reason: because it works. Italian learners will find themselves seeing the progress from Level 1 to Level 3, to a level that will give them a great starting vocabulary and a reasonably native pronunciation and tone. It's also compact - you can take it anywher with you on your phone or your car, and learn as you drive or do your daily commute with no problems whatsoever. All in all, it's a very solid course to take, and something I recommend myself as an Italian language learner, if only to build your vocabulary and to improve your pronunciation immensely.
The main problem that many autodidactic courses have is that they can tend to be very repetitive. Repetition is indeed important in language learning, but some learners may find it off-putting. Furthermore, it moves at a slow pace, being that you are supposed to only take one module a day, and the fact that you have to repeat a module if you do not satisfactorily complete the module itself. This can lead to several days of repeating the same module. Additionally, students may be tempted to forego the repetition of the module even if they aren't able to complete it satisfactorily, which will lead to inefficient learning. Another major sticking point is the relatively lesser focus on reading comprehension and writing - the supplementary coursework may be not enough for some.
It's a best-seller for many reasons, and the main reason is that it works. If you give it an honest shot, stick to the system, then continue on with another Italian learning system (say, the Michel Thomas method) after you complete it, you will have the perfect framework for success in your learning endeavors. It does work well with the Michel Thomas method for that matter, so long as you don't take them at the same time. It's also great coupled with online conversation with native speakers through italki or busuu, because that means you can practice your learnings right away. But then again, every language learner's mileage will vary - and some learners will find the repetition grating after a while. All in all, it is a solid introduction to the language that will give you a basic framework as to how to communicate in Italian, as well as a great tool to improve your pronunciation.