Currently, images and texts are checked, but there are no limits. It can be extend to your own needs.
Users can also include comments when uploading their files.
As a last resort, if there is no specified extension, and PHP can not determine the type, you can set a default extension to be added. It includes the option to limit the size and type of the file to upload. The uploader also checks if the file already exists before accepting uploads. The lastest release includes a minor bug fix that didn't allow uploader to function properly. It only allows images to be uploaded, allows you to put a size limit if you want, and checks if a file already exists.