James Robinson gives us a look at the history of Daxam in this "Superman Annual," and it goes a long way toward explaining who this post-"Infinite Crisis" Mon-El is, and what he's all about.
I'm just not sure we needed an explanation.
Actually, I'm sure we don't. But now that Mon-El has become the star of the "Superman" ongoing, I suppose some readers will want to know more about who he is, who his people are, and the world from whence he comes. Or something along those lines.
Robinson certainly gives us plenty of information about those things, and he does it in a way that's not exactly a story -- it's sort of like a slightly out-of-sequence highlight reel, or a movie trailer as Mon-El himself explains it. And what we get is Mon-El in the present, feeling a bit sad and uncertain about his own relationship with his past, and flickering images of the past with narrative commentary. It's like one of those Jor-El guided history lessons that Superman would get every once in a while. Only it's Mon-El learning (or trying not to care about learning) about Daxam.
In current continuity, as shown in this issue and referenced elsewhere, Daxam is a Kryptonian outpost. Or the Daxamites descended from Kryptonians, rather, when the Kryptonians went out and planted their flags across the galaxy. They stayed on Daxam though, while they were driven away from other planets. And Dax-Am, the Flash Gordon/Buck Rogers of Krypton, the jodhpurs-sporting intergalactic adventurer who became synonymous with the planet he conquered -- well, he's kind of the John Smith in this story and there's a Daxamite native who is his Pocahontas. The Disney movie Pocahontas, not the real one.
But Dax-Am's exploits are just a small part of this story, and we also learn -- from these flashes of history -- that Mon-El isn't just a random pseudo-Kryptonian/Daxamite alien who happens to be defending Earth while Superman's off playing Krypton Kops on the other side of the sun. Mon-El, if this issue is to be believed, has a stronger connection to Earth than anyone ever suspected.
I don't think it changes anything about the character, but it's there, and it's presented as a big revelation in the issue.
This is a fine issue, overall, cleanly presented by Robinson and artist Javier Pina. But it's probably of little interest to anyone who's not already a fan of Mon-El. Or a fan of Daxam highlight reels.