Another year, another disappointing Marvel crossover event. The premise is right there in the title. Unfortunately, building the crossover meant jettisoning a much better plot. Before I begin, full disclosure: I'm not entirely up to date on what's going on with Marvel. I haven't really read much since House of M (I know, I know). So when (say) Illyana shows up, I don't say, "hey, Magik, cool," I say, "wait, when did she come back?" Also, I came through comics (not just Marvel, all comics) through X-Men, so my sympathies are indeed likely to start there.
So, the story, such as it is. The Phoenix is coming to merge with/take possession of Hope, billed as the mutant messiah. (Nobody really argues that point in the book.) The Avengers, lead by Captain America, decide based only on a conversation with Wolverine (who totally has no reason to be bitter or biased here, no way) that this must be stopped at all costs, or... stuff. The end of the world is bandied about a lot, but it's not clear why they think this world will end. At no point (in the main book, at least) does Cap or anyone else on the Avengers side speak to anybody but Wolverine about the Phoenix. Inexcusable, since Rachel Summers (former Phoenix herself) is in the same building, but nobody speaks to her. Since Cyclops won't hand over a teenage girl under his care (who, remember, he considers the one who will save mutantkind from complete extinction) to the first non-mutant who demands to arrest her, Cap immediately throws the couple dozen Avengers he brought at the X-Men.
You can see already what side of the conflict I'm falling on. And I think it's fair to say that everything that happens from this point onwards comes about solely from the actions of the Avengers. Including the fairly well publicized plot twist of the Phoenix instead possessing Cyclops, Emma Frost, the Rasputin siblings, and Namor. Iron Man's attempt to destory or delay the Phoenix ends up splitting and corrupting it. So everything that the Phoenix five do can be traced back to him, which he actually acknowledges, rarely. Worse yet is the way the crisis is finally resolved. Hope herself takes in the entirety of the Phoenix force and uses it to reverse what Scarlet Witch did at the end of House of M- instead of "no more mutants" it's now "more mutants". Which nobody on the Avengers side acknowledges is exactly what would have happened anyways, if they hadn't meddled. The cherry on top is that nobody seems to care much about Scarlet Witch having decimated the mutant population in House of M, making Scott's argument that the Avengers in general just don't care about mutants sound a lot less crazy. ETA: After writing this review, I found out that Mr. Fantastic, of all people, called out the Avengers on their culpability here. Basically, maybe the Phoenix Five would stop beating them up if they'd stop attacking them. Considering what a massive jerk he'd been during Civil War, it makes for a pretty effective (and deadly accurate) voice of reason moment for him.
But let's be honest here. This is really nothing more than an excuse to have big, overblown battles between big name characters. What could have been an interesting story, about Hope's struggles with her "destiny" as Phoenix, is brushed to the side in favor of things like Iron Man vs. Magneto. In fact, that's all the (included) AVX tie in was, context free battles that, frankly, weren't terribly interesting. The only thing that makes the AVX issues even remotely worth reading is the "fun fact" boxes, likely included by an editor who didn't buy in to the concept, with "facts" like "Tony Stark likes to exaggerate" and "Captain America has 15 levels in guilt tripping." The last issue abandons all pretense at being serious, and ends with a "battle" between Squirrel Girl and Pixie that implies the whole mess can be blamed on them accidentally playing with Puppet Master's mind-controlling action figures.
Is it worth reading? Not really, no. There's virtually no substance here, and any attempts at such are brutally crushed by pointless battles. The entire event could have been avoided entirely if Captain America and Cyclops had actually talked instead of resorting immediately to battle. My read is that the Avengers bear a little more of the blame, since they don't even do a modicum of due dilligence before prepping for all-out war. But honestly, it probably isn't worth much thought.