I just upgraded my Wordpress blog to Wordpress 2.5. I only touched FTP once to upload a new 'automatic upgrader' plugin. This plugin then walked me through the entire process of upgrading to wordpress 2.5. It took 5 minutes to do.
If you want to do this to upgrade, but don't want to go through all the hassle of backing up your files and database, consider using this plugin - it does it all for you.