I discourage the use of Pimsleur. Pimsleur's entire method is based on infants learning languages by having them spoken to them. The problem is, infants don't have anything in their heads before that. If you're already established in a language it's going to be extremely hard to learn this way, unless the language is very similar to your own - in German we were taught this way, but much of the instructor's teaching was based on the fact that you can guess a good amount of basic German words anyway since they sound so much like English ones. Try that with Arabic. I might also add that the instructor was up there with little picture cards and making gestures and so on - the visual component to this kind of learning that is so important. If a mother pushes a ball into a child's face and repeatedly says "ball, ball, ball" over time the child will associate this sound with what he sees(a bright-colored round object) and soon enough it will be running around screaming "ball, ball" if it sees a ball. But as far as I know, Pimsleur is just several tapes/CDs filled with a bunch of foreign talk ranging from extremely basic to basic.

You will also not have any idea of grammar(since people who have learned a language from birth do not understand their own language's grammar). As well I've heard they don't even teach you to read the cyrllic alphabet. The people on this board that have been asking questions about Pimsleur usually post ridiculously transliterated phrases as "Kawtoree see-chess chess" or something of that sort. This makes me think that Pimsleur comes with some sort of book full of this kind of stuff.

Pimsleur is also a bit expensive. I would say it's more of a talking phrasebook with silly transliterations than anything else. I would more highly recommend a book that teaches you proper grammar and drills you well that has some sort of audio complement.