I think this was a great fantasy book. I admit it did re-use quite a few fantasy tropes and perhaps cliches, but overall it was a solid read. I really enjoyed Callum as a character, and there was a mystery throughout the book about what this all was for.
I think what is painfully obvious is that this book is VERY reminiscent of Harry Potter. Three main characters. Main guy gets into trouble a lot. Sneaks out at night. Has links to the Evil Villain of the book. Yep, you can see where this is going, can't you?
Still, I wouldn't call this a complete Harry Potter rip-off - this book has many elements that make it unique in many different ways. The way magic is dealt with is a bit generic though.
The plot twists in the book were awesome, although one of them I should have seen coming. I'm also glad the author(s) didn't try to wrap the whole thing up in one book, so I'm glad there's a sequel. It's not in my library though.
It felt like something else was missing in the book, somehow. Maybe some extra world-building wouldn't go amiss? There was very little connection to the real world above, and maybe that would have been nice, but I'm not going to bash it for that.
All in all, a nice little read and I might read the sequel if I come across it. 3.5/5.