I found myself constantly asking the question as to whether the experiences of the three main characters; Joy, Caleb and George, were, in fact, real or were part of their delusions. I think Cassidy did well to pose these questions in our minds as readers.
Like some other reviewers, I hadn't read the earlier work, Spilt Milk, which introduced our three characters to the world. I don't think this affected my enjoyment of the book in any way. It was an extremely satisfying read, that I struggled to put down in places.
That having been said, though, I will buck the five-star trend amongst reviewers by only offering Curious Reality a four-star review. My reasoning for that is fairly simple. There were a number of places within the story where the timeline seemed to veer out of sync, where characters were doing things that hadn't been yet explained and would be later on. Perhaps it was intentional by the author, but as a reader, I didn't like it and it upset my reading flow.
If you want something to challenge your perceptions of mental illness and the opportunity to look inside the thought processes of someone with serious psychological problems, Curious Reality, is an excellent start. It's a fine piece of work and I recommend it.
Check out all of D K Cassidy's work here: http://amzn.to/1SrbJnS