I thought the journey itself was interesting and enjoyable enough but the ending is lackluster and that soured the experience for me. A few times the zombies seemed to generate a bit of levity and comic relief though I'm not sure it was intended. The special effects are very well done and zombie swarms were a visual treat. The move away from slow moving zombies was a good one as I have never found them particularly threatening.
The post-apocalyptic world they have set up would make an interesting setting for a sequel.
I give it a solid C+