Apparently, the author has disappeared, given the number of reports and user providing fixes.
There are a couple UI fixes that would be nice to fix (e.g. clicking on the "Redirection" blue-text link at the top of various pages goes to /wp-admin/redirection... rather than /wp-admin/tools.php?page=redirection...
And a couple things that are non-intuitive the first time you get there - ie. if I setup a new group, and add redirects to it, the next time I go to the plugin page it says "no redirects found", and one has to notice that it isn't showing all redirects, but just those within the default "redirection" group.
I'll have to find another plugin (or maybe fix/release this one on my own, but I'm guessing this plugin is old enough that it is probably time for it to die, and find a new one that is up-to-date with WPs changes.