You can choose the option in what format you want to save the webpage; as html file, as google document or as .mht file. And the whole page including CSS and Javascript is stuffed in a single archive file which can be opened in Internet Explorer or in Firefox anytime.
If you want to save any type of file in your Google Drive Account, then this option is also available in this add-on. You can save any audio, image, pdf, thumnail, office or any other type of file by right clicking. You even don't need to install Google Drive Application in your computer to do this.