How useful are meta tags now a days and does it help to have more info or less in them when it comes to your forum settings?

Say for instance you had a soccer forum, would having every soccer sports relevant keywords and descriptions in your meta tags help you or is there such a thing as over kill ?

They are important, but not as important as the content on the page.

Your meta keywords shouldn't be too long, but should be good keywords. And the meta description should be a good human-readable (not just a bunch of keywords) description of the page.

Google, at least, tends to use a page's META description as the "short blurb" when the page comes up as a result, so that is a good thing to have. The keywords are not being used as much. The way I understand it, people were abusing the keywords, and so the search engines started largely ignoring them. It's better to have your keywords included in your content as much as possible.