The back of my copy of Dylan Evans's book features snippets of glowing reviews from Malcolm Bowie, David Macey, and Slavoj Žižek, all leading figures in the field of Lacan studies.
Looking through the book itself - I'm not going to read a damned dictionary from cover to cover - shows that Evans has done his homework. There are useful explanations of the various key Lacanian terms, with genealogies that show how they have changed over time.
Nonetheless, I can't help but wonder what the point of a work like this might be. I suppose if I were really stuck on a technical point, I might look up this dictionary, but that would hardly be a common occurrence. I'd be better off consulting Lacan's work, or reading an explanation in one of the gazillion other "introduction to Lacan" books that already exists.
On the whole, then, this is not a bad book, just one that seems rather unnecessary.