onlineleben - 8:44 am on Jun 14, 2012 (gmt 0)
Google say that it may improve user experience
Just looked into the HTML suggestions for one of my sites and found duplicate titles. This came from using an older page as a template for new ones and I forgot to change the title. As the title contained a city name, I herewith found the reason why my new page had a 100% bounce rate. - So, in my opinion: very useful.