First of all, i'd question my objectivity on any book that's related to StarCraft, simply because i consider myself to be a HUGE fan of the series and the story. Bearing that in mind, this is my opinion on the book.
Now, despite it being written in 3 separate books, it's basically 1 story, and as such i will be giving my experience and impression of it as a whole, not book by book, simply because it'll make a lot more sense this way.
The story takes place in the year 2503, after Brood Wars (2500) and slightly before Wings of Liberty (2504), and it follows a human called Jacob "Jake" Ramsey and a protoss conscience within him, Zamara, and a lot of other characters who've had the (miss)fortune of living this epic adventure with them.
I will try to word this as best as i can, but i have to say right away that i was BLOWN AWAY at the sheer awesomeness that is the Dark Templar Saga and the way Christie Golden presented it. This is, hands down, the BEST and most enjoyable chunk of lore that i've learned. I shit you not, i've read all 3 books within 3 and half days, taking some downtime to charge my notepad and read more.
The story is so captivating, heartfelt, action packed, there are multiple stories and plot lines being told (phenomenally, i might add) simultaneously, plot twists (some predictable, but you would have wished for them to happen so you won't care!), solid pacing (never a dull moment), character depth (i bet you'll care and understand about the protss a whole lot after reading these. And don't even get me started on R.M Dhal <3). Reading these books have been the most enjoyable thing that i've done in recent memory, constantly wanting more, and finding myself quite sad after finishing them, simply because there's no more :(
I've read 9 novels/books so far from the StarCraft universe (all within the past...2 months i'd say), and i haven't disliked any of them so far, just different degrees of like. The Dark Templar Saga blew all of that away and has easily become my favorite, which i didn't think would happen because it's a Protoss based story, and i only really like humans (Terrans). I must admit, after reading these i have developed a HUGE amount of sympathy, respect, grief, liking and admiration for the Protoss. And just in time for the Protoss based expansion, Legacy of the Void (a coincidence, in truth). Now, you might find this a bit ridiculous because it's a fantasy setting, but i've grown quite fond of and attached to this franchise and i look at it from a different perspective, i feel for it.
This might seem more like me expressing my fanboy-ism, rather than a review, but i think that if i express how i felt while reading it, and being able to share that to future potential readers (who i assume are fans of the franchise) might enforce your will to purchase/rent this book and "live" it the way i have.