Full Disclosure: I'd say that Edward Lorn and I are pals. It's not like our families take our summer vacations together or anything, but we do communicate over the Internet on a fairly regular basis. We also have worked together on a forthcoming anthology project. You may think this review is biased as a result.
Crawl, as a novella of horror, is damned near perfect. The only things I didn't like about it were pretty subjective: some of the humor fell flat, the pop culture references served to date the piece prematurely, and there were some oft-used phrases that could have been replaced with something fresher.
Crawl gains your sympathy by putting you in a car with a married couple whose wounds are still fresh after the discovery of the husband's infidelity. Then the car crashes and it's a fight for survival, but not in the way you might think. Where this story went surprised me, so I won't say any more about it. Just read it.
Or listen to it. That's what I did. I'm not an audio book person, really, but I did enjoy the presentation. The only negative thing I can say about it is that I got the 'I'm embarrassed for you' goosebumps every time the female narrator, Maria Hunter Welles, switched to speaking in her 'man voices.' But this likely only bothered me because I don't listen to audio books very often. But it wasn't a huge deal as 95% of the book didn't require that Welles switch to her various 'man voices.' And that 95% was delivered in an appropriately dramatic, clean, and professional manner.
Crawl is further evidence for the argument that the novella is the perfect length for works of horror fiction. You have just the right number of pages to flesh out your characters and to roll out the brutality and the terror in an unrelenting fashion up until the very last word. You can end a novella any way you like (with or without a glimmer of hope) without much risk of pissing your reader off; the time investment isn't the same as with a novel. There are conventions of the horror novel that don't have to be adhered to in works of this length. The characters you've grown to sympathize with don't have to come through on the other side, gasping for breath, scarred and ready to start the healing process. They don't have to come through at all.
That's what I like about the novella as a vehicle for horror. You can do what you damned well please and the reader, if you've done your job, will be surprised at where the story turns, and where it stops.