Although both fast and brilliant gallery do look similar, there is a difference in philosophy. Simplest Gallery, hence the name, is supposed to be _the_ simplest gallery module. It doesn't focus on high customizability, nor on great feature x, y or z. It's supposed to be a zero-configuration module (well, almost), just install the module, set the top folder name, and you're done. Just upload your pics in the correct folder, and the gallery is ready.
I'm not saying this is the best gallery module, but I believe every concept has it's pros and cons. Want features? Then SG is not for you. Want simplicity? Then SG fits your needs.

kindest regards,

Martijn Cielen

On Wed, Aug 19, 2009 at 3:50 PM, Tomáš Fülöpp <tjfulopp@gmail.com> wrote:

And http://drupal.org/project/brilliant_gallery :-)

On Wed, Aug 19, 2009 at 15:40, Justin Gruenberg <justin.gruenberg@gmail.com> wrote:

On Tue, Aug 18, 2009 at 9:51 PM, martijn cielen<mcielen@gmail.com> wrote:
> a while ago, I released Simplest Gallery
> (http://drupal.org/project/simplestgallery), as I really believe this could
> become a good module.

This looks really close to http://drupal.org/project/fast_gallery