Don't be fooled by the numbering. This is actually the first issue of Countdown. As the title suggests, the book is "counting down" to issue #1 from the publisher's previous weekly series 52, hence the gimmick of starting with #51.
Ideally, now, the debut issue would properly introduce the series' main characters and its premise, and make me care enough to come back for the next issue. In reality, none of it happens. Instead of proper world-building and character introductions, what the book offers is a lot of shorthand for generic superhero thing, you know the drill, please move on, nothing to see here. The story, if you can call it that, consists of a bunch of random scenes with no discernible connection, thematic or otherwise. Some vague rambling about a "great disaster" afflicting "infinite worlds" is as close as it comes to establishing a conflict. Quite why I should care, it doesn't say—if all of those worlds are as dull as the one seen in this comic, what's the loss?
The book is populated with a sorry lot of hideously designed stereotypes. There's a pale femme fatale named Duela, who introduces herself as the Joker's daughter and goes on to say things like "I may be from a neighboring Earth, but I have to maintain my bad girl cred, too." I cheer when she kicks the bucket. Another one's a gun-toting vigilante—not properly identified, but his name may be "Little Red Robin Hood" or "Red"—in turtle neck and leather jacket. His head is covered in what looks like a red wax bowl and somehow reminds me of Ruby Thursday. We're treated to a guy named Piper, who seems to be, well, a pied piper capable of talking to rats. Towards the end of the book, I swear to god, two Klingons turn up and have a shoot-out.
The most prominent character in Countdown #51 is the apocalyptic bad guy Darkseid, whose presence is evidently meant to lend more weight to the plot. After all, nothing spells "significant" like a scheming master-villain shuffling amazingly detailed little superhero figurines on a map. A scene in which a girl named Mary is released from a hospital is the one with which penciler Jesús Saiz had the most fun, I suspect, because those are the two pages in the book which give him the opportunity to draw gestures and facial expressions. What a "ray palmer" is, I'm not sure, finally - something the two aforementioned Klingons use to supremely polish their pistols with, perhaps? That's the big cliffhanger, at any rate: A Klingon has to go find a ray palmer.
If there is a point to Countdown, the first issue doesn't share it. It's a book about characters I don't know saying and doing things that mean nothing to me for reasons I'm not told. Even the cover looks like the artists were bored out of their minds—given that it's a three-page fold-out spread with all the company's major properties, that's quite an achievement.