Of course one of the first things to clear up is that there is the original version from 1978 and the remake from 2004 by Zack Snyder. This is the original George A. Romero Dawn of the Dead movie from 1978 which follows a similar yet different storyline.
The story takes place as a sequel to the original “Night of the Living Dead” from 1968, following 4 survivors, four individuals of two military / swat like men, a helicopter pilot, and his TV reporter girlfriend, who are trying to escape the zombie apocalypse and decide take refuge in an abandoned shopping mall. With plenty of resources within the mall, the survivors soon lock it down with improvised barricades to loot and equip themselves with weapons to protect their new but temporary home. However as the days goes by, tension grows and suddenly a large gang of bikers arrives. Soon the survivors are not only threatened by the zombie hordes outside attacking the barricades nor their sanity but also fellow survivors.
The film is notable for a certain line "When there's no more room in hell, the dead will walk the Earth" and that catchy phrase which has been quoted a great number of times sums the feeling of the movie.
Many interpret the movie as a Romero’s view on western society consumerism and while it’s easy to see the political statements with the setting in the giant mall being the corner stone, but what really makes the movie great, is the weird sense of realism into the proceedings as the zombie apocalypse unfolds in the storyline.
And it also has a lot of gore (including a very theatrical red color of the blood) and particularly in the end of the movie making it one of the goriest movies ever made which was also the reason why it was released unrated in the United States as the team worried it would be slapped with an X Rating. However what really works the best is the unavoidable dead and claustrophic setting of being trapped inside the mall just waiting for the barricades to breach and the massacre to start. It’s the fact that everyone knows it’s just a matter of time before the hordes of the waking dead will claim their victims.
In conclusion Dawn of the Dead is with out of a doubt one of the most important films ever made if you look over some its many reviews and it’s easy to understand that it’s often on top of the list of favorite horror films for many horror fans.
It’s also evident that it has not just inspired a ton of rip-off's but also remains to be a great inspiration for a lot of stuff even today including zombie computer games such as Dead Rising, which takes place in giant mall.