You should know that I am a HUGE fan of Cassandra Clare. After reading ten of her books and adoring every single one, I've got to know her writing style and, as such, I know what to expect from her. In short, I'd set my standards pretty high for this book… which ended up being a mistake on my part.

I've never read anything by Holly Black before so I have no idea if her writing is my cup of tea or not, and therefore I don't know whether it was her influence which ruined the book for me or if it was Cassandra Clare. Or perhaps it was the plot, the pace, the characters… there are many possible reasons for me not enjoying this book as much as I thought I would – I just don't know which it is.

I was incredibly lucky to receive an advance reading copy of this at the start of July, and when it arrived I just stared at the book in shocked excitement. Whether I enjoyed the book or not, this is an ARC of a book written by two phenomenal authors and it still sits proudly on my shelf. I just wish I'd enjoyed it more than I did.

Everyone's said it already and I really didn't want to jump on the bandwagon, but… this is like a cheap version of Harry Potter. I'm sorry, but it is. JK Rowling doesn't own the idea of kids going to a magic school, but there's a point when someone can get way too close to an idea, and that's what Black and Clare have done here. No, the story doesn't include broomsticks, Hagrid, fancy Latin spells or even wands, but what it does include are most of the major Harry Potter plot points.

The similarities:

- A secondary school where kids go to learn magic.
- Two boys and a girl who don't immediately get along but quickly become good, loyal friends to one another.
- A 'master' who gives them vague instructions that, at the time, seem to have no relevance to the overall task.
- 'The enemy' who used to be a student at the school but became evil.
- The army of 'the enemy' consists of black-cloaked evil people who wear creepy masks.
- The woods surrounding the school are full of murderous creatures.
- There's an archway in Harry Potter with a sort of shimmering veil - I'm not too good at describing it because it's been so long since I've read the books, but if you've read them you'll know what I'm talking about - and there's one exactly the same in The Iron Trial. It doesn't have the same function, but the design is identical.

And the world-building was awful. Clare's world-building is usually mind-blowing and I'm sure Black's is too, being such a popular author. But it was so vague yet complicated this time. I tried to picture the scenes in my head but I just couldn't, and it seemed to me like the authors were struggling to picture it themselves which is why it came across so messily. Perhaps an illustrated map in the front of the final edition would be a good idea?

Not only was the world-building practically non-existent, but the writing was as bland as cornflakes. I've only ever read Clare's YA books and I know this is aimed at a younger audience, but I don't believe that should cause the author to dumb down his or her writing. No matter how old a reader is, if they don't understand something in a book they'll ask someone, check in a dictionary, or Google it. Simple.

And the characters? Tamara was okay – she made me chuckle a couple of times – but other than that, all of the characters seemingly merged into one. Gone were the witty one-liners and clever dialogue I loved so much in Clare's previous books.

Was the reading experience any better? Meh. It was alright. I found myself wanting to put the book down a lot and replace it with the Twitter app, which is never a good sign, but I persevered. I got to the interesting twist at the end which admittedly shocked me but the fascination was temporary. I finished the book, and I didn't feel a thing. No excitement. No fangirling. I'm not even interested in reading the next book in the series because, really, what's the point? The Iron Trial felt rushed, messy; as if the two of them had just scribbled down all of their ideas onto a piece of paper, typed it up, and stopped there. I really don't know what to think except the fact that it simply didn't work.

Cassandra Clare is one of my favourite authors. In fact, I think she might be THE favourite. Maybe if I was slightly younger and not so analytically minded I might have enjoyed this. But the faults just popped up like flashing neon signs, one after the other, and it was so terribly disappointing, especially as it meant that my first experience with Black's writing was this.

Overall, I don't recommend this at all whether you're a fan of the authors or not, and I can only hope that someone looking to read a Cassandra Clare novel for the first time stays well away from this one.

• Buy this book at the Guardian Bookshop

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