I've been looking for such a script for a long time. It is simple and efficient, easy to use, easy to install. If you do not want to run big gallery scripts whit users, comments etc. but just want to make it easy for your visitors to watch pictures, this is the right choice.
It has even a java powered slideshow which works in all browsers.
You will need ftp acces though to upload new galleries.
Also, few more simple features will be welcome.