This rating is undoubtedly biased because I grew up playing the King's Quest computer games, but it was an enjoyable and light read. It followed a predictable format--seemingly impossible quest, with frequent obstacles overcome more by luck than skill. Still, I was left wondering for a long time how Prince Alexander was going to complete the quest, especially when more and more demands were placed upon him.
The big criticism of this book is that it could take place anywhere with any royal family--it has no specific references to Daventry except for the castle and the four members of the family (and a very brief mention of Alexander's past). In the games, characters are confronted by witches, enchanters, trolls, hags, etc. None of those exist here--the long walk through the woods is fairly uneventful (in fairness, there are a couple of creatures along the way, including one near a food cart that is a highlight of the book). I was hoping to catch a reference to places in the Daventry landscape among the long, detailed descriptions--walking past the ruins of the candy house, admiring the beanstalk reaching up to the clouds, stopping by the woodcutter's hut for a bowl of stew, or even just crossing the River Fools. It would take a bit of suspension of disbelief to accept the woodcutter's hut a fair distance from Castle Daventry, but the book already stretches the kingdom to at least a two-day walk, so I don't think this would be problematic.
The book expands upon the Daventry stories, even if it's not tied to any aspect of the games. It had a few creatures that were interesting and described well, and there was enough suspense to keep me interested. I probably wouldn't have ever read it if it wasn't for the King's Quest connection, but it was a fun way to branch out in my reading selections.