The Good
The game is simple and fun to get into, with responsive controls and a few tense challenges thrown in for good measure, such as having to shoot a string of zombies with your gun or avoiding oncoming trucks. Visually, the game has plenty to offer as well, with lots of comical undead carnage, and the free-to-play model won't beat you over the head with its transactions either. Put simply, you'll have a lot of fun with Zombie Killer Squad without having to spend a solitary cent.
The Bad
Despite the interesting blend of genres, Zombie Killer Squad still suffers from repetition. You'll basically be doing the same thing throughout the game, with no new zombie types to face later on - you may find this lack of variety a real drag. The audio likewise becomes stale over time. The same riff of rock music plays throughout the game, and the character quotes become obnoxiously repetitive.
The Verdict
It probably won't replace your favorite endless runner game, due to its grating audio and lack of diversity, but Zombie Killer Squad is still an entertaining entry in the genre, thanks largely to its comical styling and zombie carnage. Give it a shot at least.