The work put into this book is truly impressive. Just to give you an idea, let me point out that this is a Routledge course and that Routledge is the world's largest publisher of language courses. In their Colloquial courses, Routledge covers more than 50 languages. Given all this, it almost defies belief that the most extensive language course of all courses published by Routledge is not a Spanish, Chinese, Arabic, Russian, French or Italian course - it's a course in Tajik!!
While most Colloquial courses include 1000-2000 words, usually around 1500, the learner will get close to 3500 words by the time he finishes this course. And the grammar explanations are so in-depth yet perfectly explained in suitable doses that you'll breeze through on your way to fully mastering all aspects of Tajiki grammar. True, there are very few other Tajiki courses on the market but even if there were, it would be hard to compete with this one.
However, there are two drawbacks. The spelling used is conventional Tajiki ortography with the Cyrillic alphabet. That's fine by me, I don't think there's any need for using the Latin alplabet BUT... I do wish that they would have indicated vowel length. Contrary to the Persian spoken in Iran where three vowels are always long and three always short, some Tajiki Persian vowels can be either long or short. For a learner, it's impossible to know which is which and as there are no CDs to help, you cannot know when to pronounce vowels long or short. The other drawback is the lack of answers to the excersises. Having excersises is rather pointless if you cannot check your answers.
If these two drawbacks are fixed, this will truly be the ultimate language course.