The title "Avengers vs. X-Men" alone brings to mind many ideas and debates about who would win a contest, especially in light of how some have moved from one time to another over the course of Marvel history. The epic event "Avengers vs. X-Men" is the result not only of recent events in the Marvel Universe but over the whole course of the Marvel Universe and how each side interrupts the advent of the Phoenix Force upon the Earth.
Overall the story is coherent through the entire saga, though there are several rough patches that disrupt things from time to time. The custody of Hope Summers, the Mutant Messiah, and future host of the Phoenix Force is the trigger the conflict between the two teams. But things only get interesting when Tony Stark seeking a scientific way to stop the Force instead makes things worse by splitting it into five pieces that inhabit five different X-Men. The mistrust of the Phoenix Five's work and intentions followed by the mistrust of the Five of non-mutants is a recipe for disaster that the darkening effect of the Phoenix Force uses to its advantage to become whole.
Those not versed in all the recent events of the Marvel Universe up to the start of Avengers vs. X-Men won't be lost as the writers deftly put in hints without going into just plain dumping information on the reader. The subtly of the Dark Phoenix, actions of others to cause conflict between members of the Five, and the mistrust of the Five amongst themselves over time was a wonderful subplot upon looking back upon the story. The action and battles are drawn wonderfully, however they come at the cost of character development especially when it comes to the root cause of the conflict as well as the ultimate solution, Hope, who disappears the scene or is in the background for a large portion of the middle third of the story. In addition, the mistrust of the X-Men to the Five resulting in them aligning with the Avengers is alluded to but not seen which hurt the concluding chapters of the saga.
Even with some story missteps, the overall work of "Avengers vs. X-Men" is very good and a delight to read.