Doreen, Nancy and the rest of the comics' cast (excepting squirrel Tippy-Toe and the nihilist-robot-disguised-as-a-boy Brain Drain, who can only wear so many things to disguise that he's a floating brain-and-eyes-in-a-jar on top of a robot body) also wear different outfits every issue, which is totally befitting of modern college students. That's a rarity in just about any medium, but comics especially. Ditto Doreen's varying superhero outfits, the varied ensembles of heroes like Iron Man who upgrade their gear constantly, and those of fellow animal-themed heroes Koi Boi (who, not for nothing, is one of the few transgender characters in mainstream comics) and Chipmunk Hunk.
Henderson, according to this video interview with SyFy, was a film major in college. That background (plus time spent in the video game industry), informs how she lays out, stages and composes her comic book panels. This is most obvious in Unbeatable's many glorious action scenes.
From the double-page spread in the Beats Up OGN where Doreen and her newly created clone, Alleen, beat the snot out of a bunch of human-animal hybrid goons of the High Evolutionary's to Doreen beating the snot out of who I can only call Dinobot Ultron, the series' action scenes hearken back to the classic two-fisted brawling Kirby, Romita Sr. et.al. were so great at as well as the dynamism of modern fight scene masters like David Aja, and Masashi Kishimoto.
Henderson's cartoony, vibrant art is also clear and uncomplicated, which makes it easy to follow for any comics reader of any age. This is where the collaboration between her and Renzi shine brightest. Far too often, the realities of monthly comic production work mean coloring often gets rushed or oversaturated, resulting in panels that feel cluttered up with static and are at times really hard to read.
Henderson and Renzi don't have that problem. Every page is eye-popping in the best House of Ideas tradition, with a clear story flow. Given the sheer amount of dialogue and plot that come from Ryan North's scripts, that's no easy task.
North's scripts often involve copious dialogue, as well as loads of crowd work and high-energy fight scenes, and while that could sink any other artist, Henderson has shown with each and every issue that she's up to the task. Of a piece with Shelly Praoline and Braden Lamb's work on North's Adventure Time run, she's very capable of depicting both the serious and silly.
Finally, let's talk about her cover work. It's just exquisite. From a simple daydream about being cheered on by the Avengers [issue #1, vol. 1] to an homage to Superman #1 [issue #17, vol.2], they're as attention-grabbing as comics covers should be. The many variant covers done are nice, but it's Henderson's I gravitate towards.
No one knows at this point where Henderson will pop up next and what kind of comic she'll be doing. But if her work on Squirrel Girl is any indication, readers are in for a treat.