First things first: Saga is not safe for work, children, or those easily offended by nudity, sexual content, gore, foul language, and so on. Saga has all these things in abundance (and the nudity is fairly evenly spread across genders and species.)
There are very few comics I buy in single issues; usually, no matter how great the story, I'm happy to wait for the collections to come out. Saga is different. This series has given me such a burning, visceral desire to know what happens next that I may as well cable-tie myself to the rack in my local comics emporium till the next one comes out.
The heart of the premise is simple: Alana and Marko, members of two perpetually warring species, have run off to get married, quitting their respective armies. Now both sides have agents in hot pursuit of the two deserters and their newborn daughter.
The creative team do a particularly good job of depicting what happens when two cultures have been at war for a time stretching past living memory. Cynicism and black humour among the forces on the ground are matched by the callous, calculated ruthlessness of those in power. No side is portrayed as 'right'; nobody on either side believes their own propaganda any more. Both armies are composed of draftees who'd rather be anywhere but here.
In addition, we have aliens speaking Esperanto; an assassin with the torso of the Venus de Milo and the abdomen of a giant spider; a rocket ship that's really a tree (or possibly vice versa); a friendly teenage ghost who floats around trailing intestines; and a large hairless cat who can tell when you're lying. In Saga the beautiful and the disgusting lie cheek-by-jowl from the very first panel, and the story they combine to tell is believable and utterly human.
So: if this sounds like something you're up for, then go buy the first collection and await further instructions from Vaughan, Staples, Alana, Marko, The Will, The Stalk, Izabel, Lying Cat and company. Issue 9 is out in two days, so you know where I'll be cable-tied to. Bring scissors, will you?