There's no doubt this is a brilliant idea. Doors that lead to other worlds offer unlimited potential for adventure and magic taking place over a multi-volume series, as this is intended to be. Think of the Wood Between the Worlds in
The Magician's Nephew (which also starts in an attic), and you'll get the idea. Unfortunately, at least in this first volume of the series, that idea doesn't pan out too well. Will kids like it? Absolutely. But it could have been so much better.
The first problem is that the reader gets to spend hardly any time in those other worlds. What little interaction the characters do have with other worlds, of course, say it all together -- AWAKENS AN ANCIENT EVIL. Really? Another one? More problematic is that there is nary a likable character to be found anywhere in this story, aside from one very minor character who only really enters the story near the end. It's hard to care about people who are so annoying, and who drive the plot primarily through willfully dimwitted impulsiveness. There's some exciting action, quite a bit of suspense, and a whole attic-full of potential here. In the next volume, the author would do well to make the characters more relatable, and to get them into those other worlds for awhile.
From the Book:He sat up. A piece of plaster rolled down his forehead, bounced on the tip of his nose, and landed on his chest. He ran one hand through his hair, and more bits of his wall dropped onto his lap. He looked up.
Above him, two small knobs protruded from the plaster of his wall. One of the knobs was turning, very slightly. A small, scraping noise grew until a final thump rained fine plaster dust down on Henry and his bed.