I just received a request from a potential client to update his wp site to the current version from what he's now running (2.6). It's a large site, if that makes a difference.
Can someone let me know what potential risks I might be facing -- I've never updated a site below 2.7. I expect there might be issues with plugins, maybe even the theme. What else can I look for? And how difficult is it to assess possible problems beforehand? Any ideas about how much work might be involved? This won't be an automatic update obviously :)