[Note: There are spoilers in this review since so much of this issue hinges on the reveal behind the Age of X.]
In his essay "Twelve Notes on the Mystery Story," Raymond Chandler, author of "The Big Sleep" and "The Long Goodbye" gave 12 suggestions/rules for mystery stories. For the tenth note, he wrote, "The solution must seem inevitable once revealed," placing a specific importance on the moment of denouement. It's not the most important part of a mystery story, necessarily, since a lot still hinges on that initial moment of revelation and what effect it produces in the reader. In that respect, "X-Men Legacy" #247 and, sadly, the entire "Age of X" story fails when the solution to the creation of this alternate world doesn't seem inevitable or, to add to Chandler's criteria, satisfying.
That the entire Age of X is the creation of a portion of Legion's psyche has been implied and hinted at, but that doesn't make it inevitable or satisfying once revealed. If anything, it raises a lot of questions about how everyone is contained within this world, especially those who weren't in Utopia at the time the mental reality was created. Not to mention the question of Legion's abilities to rewrite the memories of so many people. These may seem like nitpicky, missing-the-forest-for-the-trees sort of problems, but they're also ones the story hinges upon. And ones that occurred to me almost immediately.
The manner in which all of this is revealed doesn't do it any favors, playing out in a long, drawn-out melodrama of teasing the reveal before an infodump. Instead of building suspense to the reveal, that teasing undercuts it because, early on in the issue, the solution to the mystery is fairly obvious and, yet, it takes much of the issue for the story to catch up with the reader.
Amidst the strong focus on the mystery, Mike Carey does craft a strong scene with Basilisk (Cyclops) and Cannonball, where the former asserts some of his true personality, while we see how much Cannonball wants that leadership role he managed to obtain in this world. Those small moments that reveal the true nature of the character, despite this being a different world, has been the strength of this story and even a disappointing issue like this one still has a moment like that, thankfully.
Along with Carey's weaker writing, Clay Mann's pencils aren't up to the standard he set in his previous two issues on this story. His work has a looser, less detailed quality to it here and relies on non-existent/blank backgrounds to a greater extent. It's not a large drop in quality, but it is noticeable compared to the last two issues of "X-Men Legacy." He still draws strong faces and gets the emotions of characters across.
Barring an amazing turnaround in "New Mutants" #24, the "Age of X" looks like a bit of a bust given this issue's revelations. Part of the problem is sheer number of moving parts that Carey uses to make this story work and how not everything adds up. Definitely a disappointment after four very strong issues.