A Gaussian Blur is distinct from other blurs in that it has a
well defined effect on different levels of detail within an image.
As the level of detail becomes smaller the filter lets through less
and less. With other types of blur (e.g. Mean Filter) the amount
let through may vary considerably.
As well as having this well defined and consistent frequency
response, certain characteristics of the Gaussian function mean
that large blurs can be applied much faster than other similar
kinds of filters.