Hi,
I had some issues installing this software so I wanted to post my fixes in case they help others.
1) My pictures often have no APP13 data, only APP0. This means that I get a lot of PHP notices right in the javascript, causing the gallery to not function. Look at your HTML source to see if this is happening.
Solution: Check if isset($info["APP13"]) for those blocks in getfolders.php and set the $title, $description, etc to '' otherwise.
I also noticed there were a few cases in getfolders.php where there were arrays referencing their index without quotes: ie $file[sizetext] or [name] as opposed to 'name'. Fixing this in the correct places helped. (I say correct places because some places looked wrong, like getimagesize("$path/$file[name]",$info), but that actually does expand correctly.)
2) In my server setup, PHP runs as whoever owns the script, as opposed to running as PHP. This means the gallery wasn't setting the right permissions to access the images or thumbnails.
Solution: I had to make my image directories myself, chmod 755 and add a line at the end of class.upload.php to chmod the images themselves to 764.
3) Large images would deliver me to a post-upload screen with no error messages, yet the image would not have uploaded. This is an issue with imagecreatefromjpeg in class.upload.php. The script will fail at this line and then terminate, without any mention in the server logs or script logs.
Solution: Increase your mem_limit in php.ini. Increasing from 16m to 32m was sufficient to handle 1.7M pictures.