The horror anthology sub genre is always a good time because it has something for everyone. Even the crappy ones are usually good for a laugh. And because they are changing storylines frequently, you at least don't have to drag through the same kind of garbage over a 90-minute runtime.
Southbound was not garbage. It wasn't V/H/S or ABC's of Death, but it wasn't garbage. Some of the special effects reminded me of a particular scene from The Mist, except Southbound's graphics were better. That says more about The Mist's quality than it does about Southbound. Acting is a smorgasbord of mediocrity in most anthology cases, and this case was no different.
The stories were more or less interesting, but the commitment to a flow of continuity in the mysterious southern desert limited the expanse you see in other anthology films that avoid this handcuff. It takes more guts to deliver an anthology in this method, which is commendable, but there is a reason the storytelling/open book/watching videos methods are more commonly used.
The metaphor or perhaps direct interpretation of Hell was the centerpiece of the film. With that in mind, the varying perspectives and imagery used were effective, but sometimes confusing. Even putting hellish creatures in a hellish place doesn't make sense simply based on the context of Hell. Now, this film clearly had a focus on the perspective of the victims. Because of this, you're stuck along for the confusing ride as much as they are. This definitely limits my necessity for calling the contextual abnormalities a negative.
I'd say I'm sure that this film was a middle-of-the-pack anthology film, but, "being sure is just a fancy way of being lazy."