I've been looking for a book at this level for some time. For once, this is a book where the 'introduction' in the title is justified. A really nice style of dialogue, very funny in some places, and the perfect amount of Harry Potter references :)
There are a couple of mistakes actually, although these might only be in the Kindle version. I've noted them and will send to the author.
I already have a PhD in QM, but I learnt quite a lot from this book. Especially the quantum information and computation chapter.
I would say that you need a first year of university maths before reading to get the full experience, however I suspect that even without this, you'd get a lot from this book.