The original Dawn of the Dead from '78 is a classic, up there with its predecessor and is considered one of the greatest sequels and horror movies of all time, and is much different in tone than Snyder's version. The original had a political/social element to it in regards to capitalism and consumerism.
Snyder's version is more straightforward in its action and horror. It's not great but good considering how far the zombie genre fell during the 80s up until that point when the remake was released. Plus, horror movies weren't good in the early 00s, so this was like a breath of fresh air.
You should definitely watch the '78 version.