Overall, DavCopy is a simple utility designed to quickly copy files up to a SharePoint server. If you need to copy files and set metadata at the same time, I would recommend using the FrontPage server extensions RPC to handle the task.
For an example of how DavCopy can be used, read the article "Working with a different type of Site Usage Analysis " on the SharePoint Thoughts blog.
Security tidbit:
DavCopy, by default, uses the windows credential set of the current user. For most cases, this is sufficient. For those cases where you must provide credentials, use the /user and /password options. Take special note that the password is not hidden ! Therefore, take care to not record your transaction in a log file or otherwise leave your password exposed.