While we've seen snippets of Captain America's origin in the first two volumes of "The Ultimates", Bendis finally goes back to the beginning and tells the tale of how Ultimate Steve Rogers became Ultimate Captain America. Understandably, there's little deviation from the usual Captain America origin, though as is his way, Bendis provides a substantially fleshed out version of events than Rogers traditionally receives.
By working Cap's beau Gail (also seen in "The Ultimates") into the plot, Bendis adds extra, welcome depth to Ultimate Cap, as well as exploring his deep desire to join the army, and his shame at being turned away due to his ailments. Cap's earliest days often go somewhat unexplored, so it's interesting to see Bendis and Loeb approaching the two early versions of the same character in this and "Captain America: White." Bendis' version of Cap is far more bitter about his situation than the Marvel Universe version ever was, and those twisted beginnings translate realistically into the gung-ho hardass we see in Millar's "The Ultimates" far better than they would for the Marvel Universe version. That alone proves that there are still stories worth telling in the Ultimate Universe that can't easily be done in the Marvel Universe, and makes me only more interested in where "Ultimate Origins" and "Ultimatum" are headed.
If there are any flaws with the issue, it's that the story doesn't really continue from the previous one. The number on the front might say #2, but there's almost nothing between the covers that marks it as such. The beginnings of a modern-era plot are sown, and will presumably tie the series together, but at this point the two issues have very little in the way of a common thread except in the thematic idea of "origins". After all, the only major addition to Cap's origin ties in with it, as we witness the mysterious appearance of a strange device that may or may not be the Ultimate Watcher (or, perhaps, an Ultimate Recorder.)
As with the last issue, however, "Ultimate Origins" is proving itself to be a strong read that expands the history of the Ultimate Universe -- past and present -- without resorting to changing the material purely for change's sake.