If you haven't been keeping up with your "Trinity" news, you might have missed the fact that this series radically changed directions a few issues back. It's clearly a direction that was planned from the start, but the first third of the fifty-two issue series -- Act 1, as it turns out -- ended with a magical wave o' re-creation which altered the very structure of the DC Universe. Think "no more mutants" but with Superman, Batman, and Wonder Woman as the targets instead. The DC trinity has been removed from existence, and reality has been changed irrevocably. Except, it's obviously not going to be all that irrevocable, since everything will return to the status quo by the end of the series.
In a way -- and I've heard this as a complaint from other readers -- "Trinity" has shaped up to be the world's longest Elseworlds tale. I don't think that's such a bad thing. "Trinity" was already marginalized, outside of the "Final Crisis" timeline, and outside of any apparent current continuity, so the "House of M"-in-the-DC-Universe approach gives Busiek and company a kind of freedom that offers exciting possibilities. It also means that the series doesn't really "matter," for whatever that's worth, but even if it's all wiped out in the end, and everything returns to normal, at least we can enjoy the year-long ride.
But "Trinity" hasn't been very impressive as a ride. Recent issues have been better, certainly, and I enjoyed the past couple more than I expected -- as we got a chance to see the larger perspective and the changes wrought in a world without the power trinity -- but "Trinity" #21 is a step backwards. The first half of the issue, written by Busiek with art by Mark Bagley, is little more than a prolonged and verbose origin story -- or origin stories -- giving background on Morgaine Le Fay and Enigma, two of the three members of the Trinity of Evil who have caused the temporal hiccup in the DCU timeline. We also find out that Despero was not what he seemed, and just as his true nature is revealed, we cut to the Busiek, Nicieza, and McDaniel back-up story, which is nothing more than Jon Stewart flying around and feeling that something's not quite right. You tend to get that in these oh-the-world-as-we-know-it-has-changed type of stories.
If you read "House of M," you'll remember how stretched out it felt. "Trinity" is like that, but over seven times as long and with way more word balloons and captions. The text-heavy pages don't add much depth to the story, though. They just repeat the obvious again and again.
Ultimately, "Trinity" might prove to be a complex diversion from the continuity-heavy DC mainstream, and the final victory of Superman, Wonder Woman, and Batman may illuminate the importance of those characters within their fictional universe. But as of issue #21, there's not all that much to recommend this series. At fifty-two issues costing three bucks each, "Trinity" seems like a gigantic investment that's not paying off.