Having not learned the lesson from the "Onslaught" disaster, this crossover is far larger than it needs to be and suffers for it. While what happens in the pages of "X-Men" and "Wolverine" is quite good, the extended story in "Cable" never clicks and Zero Tolerance's inclusion in the events of "X-Force" and "Generation X" (save for a couple of Jubilee solo issues,) is unnecessary.
Still, this is regarded as the last "good" X-over of the 90s for a reason, and it's due to the aforementioned "X-Men" and "Wolverine" sides of the story. Android-turned-man Bastion unleashes a new brand of Sentinels on the world, embedding them within living, breathing humans. Larry Hama's "Wolverine" outlines the process by which these humans are being infected expertly in ways that are both creepy and bizarre. Bastion has been manipulating people desperate for a second chance of life, altering them in horrible ways under the guise of aid. Desperate and on the run, Logan, Cyclops, Jean Grey, Storm and Cannonball find themselves trapped in the desert with busloads of otherwise innocent victims who may be about to kill them at the flick of a switch. Storywise, it's the height of the crossover, though the ending is a little corny.
The plotline in "X-Men" is not quite as strong, but Lobdell makes up for it with the introduction of arguably his best original character, Cecilia Reyes. The New York doctor is unaware she is even a mutant until she's attacked at work by Bastion's troops and suddenly finds herself on the run with Iceman. Historically in this situation, a new mutant like Reyes would be paralyzed by confusion and desperate for guidance. Instead, she's pissed off. She sarcastically picks apart everything Bobby does, finds the notion of the X-Men existing ridiculous and just wants to return to the job she had spent her life working to get. When the morlock Marrow ends up along for the ride it gets better as Reyes has another person to criticize. It's a shame that the doctor has been so underutilized since then because her debut is fantastic and her character carries several issues.
There should be enough there for the writers to pull this story off, but - unfortunately - that's not the case. The ending of "Operation Zero Tolerance" is as bad as any you will find to a major crossover. The climax is terrible, lasting a single issue that is mostly talk as Bastion is halted not by the heroes, but by government documents. And while Bastion has a devious failsafe the X-Men immediately have to deal with, it's strangely interrupted by Juggernaut hiring a lawyer and solved by arguably the worst X-Man of all time, the all-matter-munching-maggot-controlling Maggott. Despite my fondness for Reyes, she, Maggott and Marrow are not exactly the All-New, All-Different X-Men that a cover tries to set them up as.
Artwise, this book is interesting as pencillers are trying their darndest to pull back from the overmuscled art of the early 90's. For the most part, it looks great as Carlos Pacheco and Leinil Yu have some dazzling work in "X-Men" and "Wolverine." Chris Bachalo's final few issues of "Generation X" are here as well, though - admittedly - they look bizarre and not in his usual way. There's a strange kiddie vibe to some of his work. While I like a few of the teens looking younger than they did in the early parts of the series, his redesigns at this time of Banshee and Emma Frost are just awful. Sean is strangely steel-jawed and Emma looks like she's 14. Can't fault Bachalo for experimenting; often he finds success that way. But sometimes experiments end in failure.
At the end of the day, the overall package is mediocre - the continuing struggle for the X-Men for years before and years after this. Entertaining enough for a completionist, but there are a hundred X-Men books to buy before this one.