I don't know why everyone hates this movie,

I know of lots of people who totally dismiss a film as 'crap' solely on the grounds that Danny Dyer is in it. I've no idea why. Granted he tends to play the same sort of character in all his films (foul mouthed, drug using east end 'lad') but so what? John Wayne only ever played the same character regardless of the film. He always played John Wayne. Clint Eastwood, for many years always played Clint Eastwood whether he was a cop, a cowboy or a DJ. Sean Connery hasn't changed his acting style (or his accent) for a single film he's been in whether he's an Ancient Egyptian raised in Spain or a Russian Sub captain.
Yes, Danny Dyer can be a bit of a dick in reality (some of his tweets are priceless) and I heard from people with first hand experience of him that he comes across as an arrogant big head. But as regards his films, I've really enjoyed Football Factory, The Business, Severance, Doghouse and that one he did with Gillian Anderson. Although I must confess, I'm sure he has a 'drug use' clause in his contract. Virtually every film I've seen him in he's either smoking spliffs, snorting coke or dropping 'shrooms.

This film is a very entertaining, low budget 'zombie' horror comedy. Nothing more...nothing less. I've certainly seen plenty of 'serious' zombie flicks that were far worse than this.