My only real objection is that the number of vocabulary words per lesson strikes me as wildly excessive. If you're living in Tajikistan and surrounded by these words, you might be able to pick up a number of them by osmosis, but working on your own at a distance from where the language is spoken, you'll likely be somewhat daunted by the number of words cited in the vocabulary listings to the various chapters. I would not worry about this, but would learn the words that seem useful, and push ahead anyway, since the grammatical explanations and examples et al available in this book are excellent.
Michael Craig Hillmann's "Tajiki Textbook and Reader" is also a very useful resource for the language, although I suspect that most learners would probably find the Baizoyev/Hayward book a more user-friendly starter book to work with on one's own. Anyone who works his/her way through both books will have a very firm foundation in the language.
There are a few minor things that could be improved. First, Some of the vocabulary seemed to be either archaic or excessively literary. The native speakers I knew didn't recognized some of the words that I learned in this book, like pipe and faucet. Second, I would prefer a more communicative approach to language learning. I beleive that it is easier to learn a language by seeing and hearing a lot of examples rather than doing grammar drills and memorizing patterns and rules. This book does have stories and dialogs in Tajiki which are helpful, but I would like to see more. There is also a very helpful companion CD with MP3 audio recordings of the dialogs it would be even better if it were expanded.
There is a dictionary at the end of the book, but since STAR publishes a separate, even more cmoprehensive dictionary this doean't seem necessary. I would rather have had more tajik stories, dialogs, and narratives on these pages.
In spite of a few shortcomings, this is a very good language text book.