In terms of the issue itself, David continues his pattern of me liking one "The End" issue and not liking another: I wasn't a huge fan of last issue, but this issue is almost perfect. The "deus ex machina with my own personal deus" line made me LOL, because it was true -- a convenient last-minute save -- but also because it wasn't the cheap device that it usually is. Jamie does happen to have his own personal deus and Theresa arriving to save Jamie from his demon self so that he can raise a family with Layla obviously has a certain symmetry to it.
In terms of "X-Factor," I really don't even know what to say. This series was so consistently well written that it was often an oasis in a desert of mediocrity, a character-driven story that reminded you of why you read comics as other books descended into incomprehensible cross-over events or mindless slug-fests. (I'm looking at you, "Avengers" and "Superior Spider-Man.") Despite his usual talent in not leaving loose ends, David doesn't actually manage to settle all the accounts. He never really got a chance to bring the Isolationist story to fruition, we never really learned what motivated Jezebel to plot with him in the first place (since she was often portrayed as a good guy after that issue), and it would've been nice to have a better sense of what happened to Tier. Moreover, this issue itself raises some questions: I'm also not really sure what happened with Mr. Tryp here, other than him providing the dramatic fodder by calling the police, and we have no idea who the man in the black suit is.
But maybe it's actually for the best. At the end of this issue, Jamie is essentially saying that it's all someone else's problem now. You get the sense that, after the Hell on Earth War and getting turned into a demon, he's just, as he says here, done. Someone else can worry about the Isolationist when he puts into effect his plan. Someone else can try to solve the mystery of Jezebel. Wolfsbane can go find Tier if she wants to do so. All Mr. Tryp's plans and schemes are hopefully dead with him. Surely the man in the black suit has enough mutants left to persecute. Jamie? Jamie's done. At the end of the day, X-Factor in its present incarnation has been all about Jamie. If he says it's done, then it's done.
As such, "X-Factor" is also done. Thanks, Peter David, for making me so sad that this series has ended. I worry that the world of comics is instantly the worse for it, shifting the balance to the "Forever Evil"s and "Infinity"s. But, like Jamie Madrox, you can leave that to someone else to save.