Updating Fedora 26 to Fedora 27 on Tuesday was an adventure. I suspect that might be relative to what packages are installed on the computer.
On my first try, dnf downloaded the packages. The dnf system upgrade reboot is supposed to then install and clean up everything. I kept getting double boots back to a F26 login with with nothing upgraded. There was an error message that I could not find in journalctl (I really miss the simplicity of /var/log/messages).
I recently installed Linux to a router. It is a return to system V and other things that have been phased out, It works great but I digress. A full Linux distro (LEDE) in less than 256mb of RAM.
Getting back to F26 I had the presence of mind to walk away from the system upgrade for awhile and then to re-run the package download. It skipped almost everything and then updated some of the packages. This time the reboot did exactly what it was supposed to do.
Today, Thursday, I had almost 300 updates. I do not recall, over the last few years, anything like that with a new release. I love Fedora and I have both respect and admiration for the developers. They kept missing release deadlines and I suspect that the release last Tuesday was premature.