Lady Drower is probably the authoritative English language source on traditional Mandaean culture. Given the state of the community and the region, especially in the aftermath of the 2nd Iraq War, I doubt that she will ever be surpassed. This book took months to get through (primarily my fault), but it is probably the best primer on the Mandaean people that one could ask for.
This gets two stars because it is composed of hundreds of pages of detailed descriptions of various rituals and customs. While accurate and tremendously helpful from a research perspective, these portions are more then enough to put one to sleep. I cannot in good faith say I enjoyed combing through these chapters.
The latter portion of the book dealing with legends, magic, and folk lore was a pleasure to read. In studying the Mandaeans one gets a sense of the tremendous age of the people. Their religion and culture, although clearly Semitic, takes influence or has in turn influenced almost every significant religious tradition in the near east. Reading their folklore feels almost like an alternate version of the Old Testament. Despite their historical enmity, the Mandaeans share a good deal of history and culture with the Jews.
In reading about these people I feel like I am waking up from a dream which I can only partially make out. Alternatively I have the same sense that I felt so strongly in my early childhood where I was highly conscious of loosing my earliest memories and desperately trying to hold on to what remained. Like the Old Testament there is something ancient here much of which has been forgotten. What remains feels like the fleeting shadows of our earliest history.