Serious problems?

Yes those changes in bluez was what broke these things for end users not systemd so it should be blamed and yes the user has to wait until bugs have been fixed as always.

How well or poorly transitions are, is depended on the downstream handling that transition and how well it got tested before going live.

You can have a look at the Fedora feature page to get the scope of that change and components it affected ( which does not include systemd or dbus for that matter ) and this transition required coordination between the kernel team, the desktop teams and several package maintainers and testers to test all those changes then for example compare that with how the transition was handled in the distribution you use.

1. https://fedoraproject.org/wiki/Changes/Bluez5