Good speculative fiction always has a great premise, a tantalizing "what if" question or scenario it presents to a reader. The real trick is to take that concept and do something entertaining, moving, or thought-provoking with it. "Imagine a Friend" does all of that, and more, to varying degrees, resulting in a reading experience that has a lot to offer fans of such tales.
This story, and its big hook, which is something one might successfully predict via its title and description, is well executed, and gave me a satisfying blend of things to enjoy and ponder, outright revealing certain aspects while leaving others intentionally vague throughout its duration. I didn't love every aspect of the narrative, as there were occasionally certain elements that didn't quite land or click for me, but the overall effect was solid and compelling, causing me to breeze through the book in just a few hours, and easily overlook any of its "rough edges."
To sum up, I found "Imagine a Friend" to be an intriguing and worthwhile read that confidently and convincingly delivered on the clever and stimulating idea at its core. If you enjoy speculative-fiction tales that lean more toward the fanciful while still keeping a foot firmly planted in classical reality, I imagine that you'll really enjoy it, too.