One reason why I chose to learn Czech with the Pimsleur course was because I hadn’t done a Pimsleur course before and I want to test as many different types of language course as I can find. To date I’ve tried quite a few Colloquial and Teach Yourself courses, one Rosetta Stone course (Russian), which I’ve yet to finish, and a few lesser-known courses.
When comparing language courses for the same language you can’t start each one from the same level because you can’t erase from your memory what you’ve learnt in each one before trying the next one. If you try comparing a course from the same series for several different languages, you often find that the courses are not identical – the basic format is probably the same, but each one has a different author and the quantity and quality of material varies. Each language also presents you with a different set of challenges, and you may find that some types of course work better for some languages than others.
Generally I find that no single course is sufficient to learn a language, so I often use several different courses during my studies.