I have used it many time, you cannot always include every word it suggests though. It's just telling you what people searched for in the last 30 days, if it doesn't apply to your hub there is no use adding it.
Funny story, I had a hub about making apple pie that I had titled "Easy as Pie, Rustic Rainy Day Apple Pie." Title tuner suggested I add the word "woman" to the title. Apparently it was picking up people searching "Rainy Day Woman" the Bob Dylan song. So I tried it, just out of curiosity, but the "Rainy Day Woman's Apple Pie" didn't result in any additional visits, and I changed it again after a few days.
That said, I have many times seen increased traffic after adding words suggested by Title Tuner.