Well done to the developers for this great FREE component. Well worth a donation
One minor thing is that certain file extensions give more than one icon is displayed against the attachment which can make the output a bit "messy". As a future, perhaps allow editor to choose if more than one icon displayed or not. Otherwise a great little extension.
The display of multiple icons is not a problem with the Attachments extension itself. It is due to other extensions that add icons to the display images such as the multithumb plugin.