Over the past year, for a project I've read a wide variety of encyclopedias on religious movements, religious issues, and religions in general. Out of more than 20, Smith's encyclopedia is certainly the best. Unlike some volumes of the "Concise Encyclopedia of X" series, Smith has reasonably detailed entries, ranging from a paragraph to several pages. The articles themselves are very clear and well-written, with suggestions for further reading. The articles cover an enormous range of personalities, doctrine, and history of Baha'i. Fascinating.
I have been impressed by the clarity and eloquence of the short essays under such difficult to describe topics as "the soul." The references to primary works where the reader can find more information are accurate and easy to use, although the Encyclopedia itself does an admirable job of answering most of the questions I've had. It is richly illustrated, with an easy to read type.