This plugin saved me a few coding hours when I needed some widgets on specific pages on a site.
The only thing I can think of to make this plugin better would be to maybe offer a check box type option where a less experienced user can simply click a box next to the posts pages, categories, etc. that they want the widget to show up on. Might be a little cumbersome if there are a lot of pages on a site, but maybe put them in a collapsible menu organized by posts, pages, categories, etc.
Still a 5 star regardless of the wish list :-)