Ok, technically this is a 3.5 star, but I'll give it 4 because looking back at all the books that lead up to this, this one was somewhere in the middle.
To start off, if you're like me and want to know more about Garak, Cardassia and all those wonderful (awful, terrible) characters, don't be like me and start at the end (with Enigma Tales, which I feel I should re-read now that I'm all caught up).
Wanna know Garak's backstory? Start with Robinson's A Stitch In Time
Wanna know what it was like being a Cardassian during The Fire and Dominion War? Read it from Rugal's POV in The Never Ending Sacrifice (the beginning of the Cardassian books by Una McCormack)
What about Garak after the War and he makes it back to Cardassia after becoming an Ambassador? Next on your list is this book, Crimson Shadow, then.
How do you sum it up all neatly (enough)? Finish with Enigma Tales.

I really wish I had started with this one, at least, before reading Enigma Tales. There are some great characters that Una has created that continue on into ET. I think that's definitely her strength is in her characters. Yeah, it gets a bit slow in places, and I am easily confused when there's a lot of characters to follow (and having similar names starting with the same letter just does me in). But all in all, a great book to read if you're interested in what is going on in Cardassia about a decade after The Fire and how things are holding up politics-wise (not well and shadily) and what Garak is up to (being his wonderful sassy self and taking on too much at once, but happy to be home). And Parmak. Lovely, wonderful Parmak.

Spoiler

Honest truth? I started with Enigma Tales because someone online in the Garashir fandom was like "read this! it's great! almost makes Garashir canon!" Not really, but it was enough to get me into the Star Trek novels and with a little more researching into the chronological order of these books by Robinson and McCormack, I was able to follow Garak through his life, before and beyond what we watch on DS9. Is it great for G/B shippers? There's a few tiny mentions here and there to enjoy, but don't read it just for that. Read it to learn what happens to Cardassia after the war, what happens to Garak, and grow to love the characters, both original and canon. And learn about the amazingly loving partner that is Parmak and consider that perhaps he might be better for Garak than Bashir? All our poor old lizard needs is someone to love and forgive him. <3