[Updated Review] The newest free version (updated 3 weeks ago - or approximately Sep 10, 2013) is a great improvement over the original. The fast-clicking bug has been fixed, and the plugin installs normally, without the necessity of modifying the functions.php file. However, it is now possible for one person to vote multiple times from the same IP address after an interval of a few minutes. The plugin needs to check IP addresses, and it apparently does not.
By default, the plugin displays both "Like" and "Dislike" with thumbs-up or thumbs-down icons after both posts and pages. That will probably suit most users.
If you want to change the default behavior, choose "Use Template code." This is for more experienced users, since you will have to modify your functions.php file in a child theme. You will have to find the post and comment sections in your file to add the code in the proper places. (Do not modify your main functions.php file, because it will be changed with the next theme upgrade.) There are no instructions in the plugin repository, only solicitations for the "Pro" version which has includes a widget showing popular posts.
It does seem a bit self-serving for one of the developers to "review" the plugin (below my review) and give the plugin 5 stars!