Ranked in these QuestionsQuestion Ranking
Pro Graduated interval recall
Spaced repetition in and between lessons are timed for maximum recall. This also means you can't skip days between lessons, or work ahead. Each level takes one month.
Pro Very effective for beginners
Pimsleur is based on proven memory science, it's not perfect, but it is very effective. Intermediate learners may not get as much out of it.
Pro Learn while you commute
Pimsleur uses daily 30-minute audio lessons. You can probably fit this in while you're driving to work.
Pro Principle of anticipation
Rather than simple listen-and-repeat, you also have to translate phrases and answer questions in the target language during the lessons.
Pro Teaches pronunciation well
Uses the backchaining technique with native speakers.
All the CDs for one language cost nearly a thousand dollars. The .mp3's are about half that. Your local library may carry the CDs, those that don't may be able to get them via inter-library loan (ask your librarian). You can also find them used and re-sell them for nearly as much (depending on how long you want to wait), after you finish. Be certain to get the same edition for all levels.
Con No writing practice
Pimsleur is an audio-only course. This can be easier for beginners learning languages that don't use the Latin alphabet, but for serious language learners, it's a gap they'll have to fill using something else.
Con Limited vocabulary
It teaches hundreds of words. A great start, but not enough to achieve the thousands required for fluency, even with all three levels. Pimsleur deliberately focuses on the most common words of the target language for maximum recall.
Con Too slow-paced and repetitive for some learners
If you learn quickly, you may find that the 30 minute lessons covering only a small handful of vocabulary move too slowly for you.