Strange, mine sailed right through and took about 17 minutes at max. One of the fastest installations of OS X, ever. I did a clean install though, you doing a clean install or an upgrade?
I'd advise waiting it out. Others have had the same problem, some even taking 2 hours or so to complete the install, despite the wait time being a completely different time.
My computer got stuck multiple times but eventually rebooted into Yosemite, maybe an hour later. I couldn't tell how much estimated time was left because my entire screen was covered in artifacts and lines. Don't know what that was about but Yosemite doesn't have those glitches.
I actually gave up. Tried to install it 4 times and it froze everytime. I'm not that desperate and don't have the time to waste troubleshooting. I'll wait for newer iterations of the beta.
Yes, mine is stuck at 20 mins. It's been on 20 mins for the last hour. I'm not sure If I should wait it out, or reboot in safe mode like some have suggested. I'm slightly annoyed at this point. Never has an upgrade operated in this manner. Apple should be embarrassed.
Short story: the installer removes then re-copies everything in /usr/local. Some people have lots of stuff there. The installer does not accurately report the time remaining while it is taking (sometimes hours) to copy those files.
You can see what's going on in terms of file copying if you open the log:
I am currently waiting for yosemite to finish doing a clean install on macbook pro late 2008 and it seems to be taking forever to move on from the setting up account screen was wondering is there anything i can do to speed this up as i just want to get on with reinstalling my programs on the mac