Let's get the obvious things about KILLING GIRL #1 out the way first. Yes, artist Frank Espinosa is a very stylish artist, especially when he handles the coloring as well as the brushwork, as he does here; the art here is easily the best thing about the book, to the point where I wonder whether Espinosa's absence from the series in the last Image solicits (Toby Cypress is listed as artist, instead. Having seen Cypress's art in The Tourist awhile back, it may actually be an improvement, but I digress) will hurt the series' chances with the audience in the long run.
Espinosa may be too stylized for his own good, especially on this book - his retro '50s sense of line and color is not only at odds with the subject matter. It's too attractive, for want of a better way of putting it - it's not that there's an interesting cognitive dissonance (Hi Johanna!) between the two, but that they just plain don't work together - and also, at times, hard to read what's happening successfully. It's frustrating to read, because you know that Espinosa's a talented artist; he simply needs an editor to tell him to take another pass at a page every now and then for his stuff to be completely drop-dead wonderful.
The story, meanwhile, doesn't live up the art, no matter how flawed the art may be. Sad to say, there's nothing in the writing that you've not seen before, and done more successfully, at that; the dialogue is cliched, the plot relies on coincidence too much (The boyfriend of the assassin's long lost sister just happens to run into her at a stoplight? Really?), and the whole thing is slathered in narration that makes you feel as if the lead character has only ever read shitty airport spy novels in her entire life. Which is to say, it's not a very good story, sadly.
The end result is a book that pairs the most generic of writing with art that could do with being a little bit more generic, which is as unsatisfactorily Eh as it sounds. An oddity, but not necessarily an interesting one.