I use the "thanks" button mostly to show I've read the post.

When a specific thank you seems to be needed, I will actually post that! I find it is impossible to post to everyone...so the thanks button is helpful to me to just let them know I am reading and appreciate their post. If I have any comments to add or whatever I will create a new post in that thread. ( I also try to keep a low profile and let the members help each other etc.).

I think thread starters who make threads use the "thanks" button to reinforce those who are replying to them. And remember some people are impaired and find typing or posting difficult. The "thanks" button is only one click. Easier for them.

So I agree with Chemar....it is really up to the person how to use it. I find when I visit other places that use vBulletin, the "thanks" button is often not enabled. I rather miss it. I think it is a very useful feature, myself!