After about 4 hours, I decided to force a power off.
When it rebooted, it said let's take a tour of El Capitan!
I have not done much with it yet, but the important stuff (wifi, Safari) seem to work OK.
Thank you for this. I was also stuck at 'Terms and Conditions' with no ability to go forward or back. I forced shutdown and rebooted and everything seems fine.
I originally upgraded to El Capitan via a local account, no problems.
I then added a new administrative iCloud account and restarted.
I was unable to log in via the new iCloud account because it would not recognize my password.
So, I re-logged in via the local account, then I switch users to the iCloud account and it then recognized the password.
At this point I was asked to setup my iCloud account and it took me to the 'Terms and Conditions' page where I became stuck.
Thanks to your OP and solution, after force restart I am able to correctly login via the iCloud account and everything appears to be working. I have yet to see the 'Terms and Conditions' page again.