Interesting if you have some desire to see what operating systems visitors are using. Really not at all useful.
Again only useful if you have some morbid curiosity about what countries people are calling in from. It does confirm that on my personal blog most people come in from England, France, and sometimes Germany to read about the werewolf private detective. Here on this blog the number of visits to Yuru Yuri and other anime related posts tend to match up with the number of visits from Japan.
Thanks to a yuri doujinshi site for the flag counter.
Fun fact: for the past eight years I had a “mysterious” follower on my personal blog. As soon as I mentioned these stats in a comment, that follower disappeared.