The initial reaction to this self-study course is that it is far too advanced for the beginner. It starts quite simply, then and appears to race off into the distance. But learning a new language is never easy, and for a retired person the learning process becomes ever that much slower!
However, if you're serious about learning the language and you are willing to persevere you can eventually make real and satisfying progress. Most of the information you need is in this book, though it does help to have alternative texts available to stretch the vocabulary a little - and, of course, a good dictionary. (This latter not so easy to find!)
The CD's are a real help and whilst each new lesson at first sounds totally incomprehensible, you find that as you progress you can return to earlier tracks and pleasantly surprise yourself that you are now understanding spoken Bulgarian at a reasonable speed. Without the CD's, the course would be impossible for a beginner, and I imagine that manipulating the tape cassettes would become far too tedious to be helpful.
This course is far, far better than a number of courses I have seen published in Bulgaria!