This book was alright for me. Tana French's The Likeness was so much better. 
 I will try to give my honest opinions on it, both of what is great about the Secret History and what are its shortcomings. I will inevitably compared this book to French because the concept of both books are strikingly similar, but since literature is a subjective area, I of course respect people's preference for one book over another. Warning: mild spoiler below in regarding to theme 
 Some similarities: 
 1. There exist a group of five close-knitted liberal arts student who are outcasts and have predilection for an abstract, liberal-art like subject. In the case of Tartt, it was Greek mythology. In the case with French, it was literature. 
 2. They lived in an old, beautiful country house, detached from the world and they are the type of people who like to converse about Peloponnesian war or the tragedies of 19th century British Gothic novels as dinner talk. They are extremely intelligent, mysterious, charming, yet they all seem to hide something sinister beneath their polite facade. 
 3. Both stories revolved a murder of a student within the group, and the subsequent disintegration of said group . The person who is murdered are both revealed in the beginning of the story, so it's not a spoiler of who will be killed. In the case of Tartt, it was Bunny. In Tana French's, it was Lexie. 
 4. In both groups, there are some similar personalities: A cold and calculating de-facto leader, a guy who might or might not be homosexual, a charming girl who kind of reunites the group, a guy friend who is very friendly...etc. In both groups, there are some secrets that aren't revealed to outside member, and the group as a whole sometimes act very suspiciously. In both case, the main character (Richard in The Secret History and Cassie Maddox in The Likeness) try to understand what cause the murder to happen. 
 However Tartt had some failings: 
 The Secret History is way too long for its own good . It was around 600 pages. Initially, it has a great buildup, but it falls flat around 200-300 mark since the murder is revealed by the middle of the book, and 50% of the rest of the book is just one tragedy set after another... dragging on and on and on. What Tartt don't realize is that once I know why Bunny is murdered, I don't give a FUCK about how these kids are suffering anymore, because I cannot sympathize with them after I learn why they kill Bunny, which brings me to my next point: 
 The motive of the murder : I will not give away the spoiler, but in Tartt's case, it was an EXTREMELY SELFISH reason. It was quite selfish that even though I was quite intrigued with the ideology that leads to the murder itself, (which, minor spoiler, is kind of about hedonism) just make me say: Uhm, these kids are so fucking privileged and I feel 0 ounce of sympathy to them now. I don't even care if shit happen to them. . 
 In the case of The Likeness: 
 - French had an interesting synopsis: there's a detective who infiltrate the friend group to discover the murderer. There was always some tension. Who is the killer? Why did he/she kill the girl? Will the detective be safe if she lived in the house with a murderer? 
 Tartt's on the other hand doesn't really have that much tension. Sure, it seem the group in The Secret History kinda hate Bunny but uhm, that's expected by the reader because Bunny is end up murdered. There wasn't much going on in the first half actually. All the kids do are smoking, drinking, and talking boring stuff. There was some odd behavior but it is all revealed by the middle of the book so that's that. The Likeness, on the other hand, has a detective going around hunting for clues, so we are thrilled to turn the page as more and more stuffs are uncovered and the twist isn't revealed until the very end. 
 - The motive of the murder in The Likeness is much more sympathetic. French's murder goes along the line of friendship, love and an unrequited obsession with the unobtainable. It is more tragic in the sense that we slowly come to love these close-knitted liberal arts student and identify with their idealism, whereas in Tartt it was unrealistic and selfish, and also quite accidental and stupid, in my opinion. 
 The best thing about the Secret History is basically the prose. It is written in the veins of Neo-Romanticism style and the atmosphere is so amazing that you feel like you are transported to Hampden College and lives with these students. I also love the main character, Richard Papen, and I do feel like I identify with him somewhat, alongside with Henry Winter. But other characters seem to be these cardboard cutout of wanna be literary theorists and I-am-smarter-than-thou-and-too unique-for-this-world. This get old fast when we readers are treated with pages of purple prose description with basically nothing going on beside Papen's mental meltdown, these kids go to a picnic, play piano, read book, eat dinner, go to sleep . And once the whydunit is revealed, we already lost interest and can't be bothered to give a shit about these characters. It's like Wuthering Heights , whining, melodramatic and boring. I don't feel the warmth and closeness of the group in The Secret History as I did with The Likeness. 
 Again, these are just my opinions though, I am pretty sure other enjoy more about the story's literary merit more than I do.