So far, most of the "Age of Ultron" tie-in issues have abandoned any attempt to continue its parent title's ongoing story, opting instead to tell a one-off tale based in the world of the reality-bending event, but in "Uncanny Avengers" #8AU, writers Rick Remender & Gerry Duggan and artist Adam Kubert take a different approach. Since UA is already telling a tale about time travel and alternate realities, the Brian Michael Bendis-fueled Age of Ultron manages to fit into that framework just fine.
Set in the alternate present established in the core series, the issue sees Kang mentoring the Apocalypse Twins (Uriel and Eimin) through an encounter with the AoU version of the Defenders, including Colonel America. Since they're using the "real" version of the villains (that's real compared to the destined-for-deletion alternate versions of the usual cast) Remender & Duggan take the opportunity to flesh the Twins out. It seems that as villains go, they've not always been the unadulterated killing machines Kang would like them to be, which raises interesting questions about the direction of the story and turns these otherwise two-dimensional characters into slightly more complex antagonists.
With regard to the heroes, Remender & Duggan use the opportunity of an alternate timeline to hint at what might be in the "real" Marvel Universe, rather than simply rolling out wacky versions of the series' cast safe in the knowledge that there are no consequences. Relationships and roles are explored in counterpoint to what we know about each character. Seeing Havok as the legitimate spokesperson and leader of a mutant group (albeit the Morlocks) seems particularly important in showing us the character's potential fate under the right circumstances, and what he might give up to get there.
Visually, the book takes the unusual approach of illustrating a dystopia in a way that's almost prettier than the "real" world is under the arc's regular artist, Daniel Acuna. Adam Kubert's pages are detailed yet fast-paced, with bold, expressive characters and a wide variety of layouts. It doesn't necessarily matter one way or the other to the story, but from a consumer's perspective, it helps to have a top-flight artist illustrating what might otherwise be seen as an easily avoided fill-in issue. Regardless of content, the chance to see Kubert draw an issue of "Uncanny Avengers" is enough to justify the cover price on its own.
As crossover tie-ins go, this is perhaps the best readers of the series could expect: something that continues the title's story without slowing it down too much. Admittedly, if you're looking for "Age of Ultron" content, you may well be disappointed because the relevance to the event is minimal and skippable - but if you're reading "Uncanny Avengers" on an ongoing basis, don't be fooled by the "AU" numbering: this issue is worth owning.