If you install from a current Rawhide Workstation live, e.g.:
and boot the installed system, it boots to gnome-initial-setup - so far, so good. g-i-s works fine, apparently, it gets all the way through user creation. You click "Start using Fedora" and...it drops back to a console showing boot messages. That's it. It never reaches a desktop, or GDM.
tty2 seems to be occupied by something when this happens (if you switch to tty2 it just shows a black screen, it never shows a console login prompt). tty3 shows a console login prompt and you can log in successfully as the user you just created. Looking at the system logs shows an at-spi-dbus-bus.service failing to start likely due to more complete fail on the part of the dbus-broker Change, but nothing else obvious.
If you reboot the system, it boots to GDM, and you can log in. It then runs the user g-i-s, which it should not for the user that was created by the 'no existing user' g-i-s process. Once you make it through the user g-i-s, you finally get to a desktop.
If this also affects F29 (as I'm guessing it will) it will be an F29 Beta blocker, but will wait till we get a working F29 compose to verify that.
Assigning to GDM as I'm guessing this is along the same lines as https://bugzilla.redhat.com/show_bug.cgi?id=1618794 ...
Created attachment 1480177 [details]
journal contents from the affected boot
openQA testing of latest 29 compose shows the same bug:
Proposing as a Beta blocker per Basic criterion "A system installed with a release-blocking desktop must boot to a log in screen where it is possible to log in to a working desktop using a user account created during installation or a 'first boot' utility."
Discussed during the 2018-09-04 blocker review meeting: 
The decision to classify this bug as an "AcceptedBlocker" was made as it violates the following criteria:
"A system installed with a release-blocking desktop must boot to a log in screen where it is possible to log in to a working desktop using a user account created during installation or a 'first boot' utility."
gdm-3.30.0-1.fc29 has been submitted as an update to Fedora 29. https://bodhi.fedoraproject.org/updates/FEDORA-2018-81a7d8ed40
I have tried to verify this and I can confirm, that the new version of gdm (#4) solves the problem.
After the reboot, it boots to gnome-initial-setup, creates the user and then logs in the newly created user.
The only flaw, I have experienced, is that gnome-initial-setup actually ran twice. For the first time, I clicked Next on Geolocation service and that usual stuff, then it let me create the user, and then I went through the same process again for the next user.
gdm-3.30.0-1.fc29 has been pushed to the Fedora 29 stable repository. If problems still persist, please make note of it in this bug report.