Henle Latin is an outstanding program in that it teaches the Latin grammar through translations and select readings, making it interesting to the student.

The exercises and readings in Henle teach Roman and American history, the difference between the pagan and Christian worldviews, and the difference between the virtues of the natural man (of whom the Roman was the greatest type) and the virtues of the Christian man, which are possible only through grace.

Henle is a superior text in that it uses a vocabulary limited to roughly 550 words, allowing the student to master the grammar concepts without being unduly burdened with vocabulary memorization.  (The competing text has a vocabulary of just under 2,000 words, by comparison.)  I believe this feature alone allows for a greater number of students to gain mastery of the language and graduate to reading unadapted texts.