My wonky opinion, very subject to change in a few months.
So many spoilers! Must re-read it after I can get to many of the classics in this book. I approached this book as an introduction to Russian Lit. I was hoping it could shed light on what makes Russian Lit so cool and unique. Before reading it, I only had a small understanding of Russian Lit.
After reading it, fabulous discussion about Dostoevky's Gothic influences. I like him even more now! The introduction took me forever to read! It was so packed with must know stuff about Russian Lit. For a newbie, best pages of the whole book. The last chapter, his commentary about the early critics of Russian Lit, were interesting and concise. He mentions a lot of 'who's who in the early 1900s and what they said about various Russian works/authors. It sure saves a tonne of time having it all summed up!
I'm wondering if some of his critiques were outdated though. (ie. Doctor Zhivago and how it relates to the Jewish struggles of the time. I'm baffled by this argument.) As a newbie to Russian lit, I certainly couldn't say if there are faults in Garrard's arguments or critiques. I may not be familiar enough with some of the Russian authors in the later chapters of the book to say for sure.
I do have a respect for Constance Garnett now. Her work was a labor of love and she sure helped to bring Russian lit to the West. The recommended translations in the appendix are a great starting point for navigating all the options. The list is a bit dated, so the newer translators aren't mentioned. (Pevear and Volokhonsky -- wink, wink)
If it's at your library or is easy to get, I'd recommend it for new folks to Russian Lit. It's riddled with spoilers though, especially in the middle chapters. -.-