While not a substitute for direct oral instruction, it is helpful for a "refresher". Its been years since I recived the empowerment for the practice, so its a great tool to remind myself of seed syllables, colors or sounds used during the practice. I have some shorter instructions from my teacher, but the depth of the book works really well esp. with the sleep states and various stories Rinpoche uses througout. If Chenrezig is a main practice for you, I can't think of a better book to use than this one.
This text provides clear and concise instruction for deity meditation. It includes instruction for beginners on visualisation. It also has pictorial help for visualisation of HRI and for disolution of the HRI which I found very helpful.