This is certainly Faivre's most useful book for a broad knowledge of esotericism. It's really not a book, actually, but a series of articles and an annotated bibliography, but it holds together well and is readable just as it is. The translation is solid--it's the work of Joscelyn Godwin, a student of Faivre's, whose works are also very useful.
The nice thing about Faivre is that he takes the subject-matter seriously, which isn't exactly usual, and he goes into some depth about the 18th and 19th century thinkers he's interested in (von Baader, notably). For an introduction to a somewhat lost period, i.e. Enlightenment occultism, you could hardly do better than Faivre. He was until recently a professor at the Sorbonne, and has founded a whole little school of scholarship on esotericism (Hanegraaf and Godwin leap to mind).
On the down side, Faivre is a weak phenomenologist, and this leads him occasionally into dubious categorical divisions that distort the material. To put it more simply, the distinctions he makes among esotericism, mysticism, and occultism are problematic, and lead him to cut off from view a lot of interesting figures. The reason, I think, is that he believes that a certain sort of syncretic esoteric viewpoint is the best hope for a spiritual revival of western humanity, and so he focuses on the thinkers he thinks best support that goal.
The very best thing here is his annotated bibliography. It's not perfect, to be sure, and now a bit dated, but there is nothing like it since Albert Caillet, who's so encyclopedic as to be unhelpful to a beginner (he's also very dated, of course). If you're serious about learning something about the occult in later European history, you need to read through this bibliography and take Faivre's advice.
I don't think this is a book that a serious student should be without. At the same time, I would advise a little caution with his glib definitional and methodological pronouncements.