More than half a century ago Jacques Barzun wrote, in Teacher in America, something I feel strongly about everyday when I go to work and struggle to teach with the Cambridge Latin Course:
We have all had in our hands these little works, which start off "Wie geht's heute mit dir, teurer Hans?" and go on with chitchat, anecdotes, and pictures of Salzburg. This is chumminess misplaced. Let the teacher say "how do you do" and let the book remain what a book should be -- a systematic exposition of the subject, in which the student can find what he is looking for. Nothing is more exasperating than to have to wonder whether the subjunctive was given together with a description of Bremerhaven or later, with the sad story of Struwwelpeter. Besides, no student is better off for having all the verbs given in bits, half a tense at a time.Instead of Bremerhaven we have the remains of Pompeii. We're not lucky enough to have Shock-headed Peter, but the ghost of a gladiator makes a brief appearance. The subjunctive will wait for the second or third year, along with probably the ablative and many other useful things. Instead of chitchat we have an unending stream of Latin in the vein of 'See Spot run': servus anulum conspectat. servus anulum capit. servus abit. *yawn*
The 'course' is useful if you have little more Latin than the book will teach you, and even less history and culture.
The problem with courses is that they're proscribed -- teach the genitive if you wish, but the kids won't see one for another year. Every time you step off the course you're bound to wonder whether you should ever step on again.