Well, I sure didn't see that coming!
The revelation that Brutaal was Superman was awesome, really. Robinson had gone to significant lengths to establishing just how powerful Steppenwolf is, with him and his three "dogs of war" eliminating hundreds of thousands of soldiers of the World Army seemingly in a matter of minutes. To have Brutaal unexpectedly cleave Steppenwolf in two as he pronounces his victory over the world was shocking, to say the least.
As I was reading Steppenwolf's speech, I found myself trying to remember how Steppenwolf killed Superman in issue #1. I remembered that Superman engaged Steppenwolf after he killed Wonder Woman, but I couldn't quite remember how he died. A few pages later, when Robinson revealed that Superman was still alive, I did some Googling and remembered that Superman actually exploded under attack from parademons. It, obviously, raises some question as how he could still be alive (if he is, in fact, Superman). Did Desaad somehow get his hands on Superman's remains, resurrect him, and program him to take down Steppenwolf? (Desaad didn't seem so pleased with Steppenwolf in issue #15.1) If Desaad is manipulating him, will Superman power Desaad's Boom Tube to re-establish the connection with Apokolips? If Desaad wasn't involved in his resurrection, how was he resurrected? Moreover, if it wasn't Desaad manipulating him, how did Superman suddenly come under the sway of Darkseid after he was resurrected? Although I'm excited about the possibilities, we're going to need really good answers to these questions so that this revelation doesn't feel like a convenient stunt.
Beyond the Brutaal/Superman revelation, this issue is important because we see the Justice Society in action essentially for the first time. Although it's missing Hawkgirl, it's pretty much every other Wonder that we've seen so far. I thought Robinson made a good call bringing them together not to fight Steppenwolf, but to save the survivors of his onslaught. One of the divisions between the two sides of Wonders throughout this series has been Atom's belief that only heroes affiliated with the World Army should be fighting and Green Lantern's belief that the Wonders should exist independent from such political manipulation. By removing this hierarchy question from the equation and turning the Wonders' alliance into a rescue mission, Robinson brings the team together in a way that feels organic, reminding us that they're all heroes seeking to make the world a better place. Moreover, with the World Army decimated, sanction is clearly going to be less of an issue than survival. My guess is that the team is here to stay, operating in the absence of the World Army to protect Earth (though I expect Atom and Green Lantern not exactly to agree on who's leading it).
After 19 issues (including #0, #15.1, and #15.2), my only complaint with where we are now is that we've had too much of a good thing. Although Brutaal's reveal was powerful, it would've been more powerful had I any memory of seeing him before this issue. The only henchman of Steppenwolf I remember is Fury, who I last remember seeing in pursuit of Big Barda and Mister Miracle, though I can't quite remember where we left them. This reveal would've been more powerful if we would've had time to see Brutaal as Steppenwolf's trusted lieutenant, making his betrayal all the more profound (like Xorn -- before the ret-con -- in Morrison's run on "New X-Men"). But, Robinson has been juggling so many characters that he's barely had time to focus on the Wonders, let alone the villains.
Most of my early issues of this series are at my folks' house, but I'm tempted to have them send them to me so that I can read the whole saga from start to finish. Robinson leaves us here with the real sense of the first part of "Earth 2's" story complete: the Justice Society is born, the real villain is revealed, and the situation is indeed dire. I would've loved to have seen him tell the next chapter but I have to thank him for delivering the one that he did. This series remains the best part, despite its flaws, of the reboot and it's all because of him.