Yesterday I upgraded my notebook from 14 to 15.
Problems:
1st: it deleted network configurations.
2nd: rpmdb was left quite messed. Several dependencies non satisfied. As
this particular box was already upgraded from 13 to 14, there were
problems dealing with very old things (fc13 stuff). Much of upgrading
had to be done by hand (including uninstall & reinstall packages). Yum
failed short.
3rd: kde & kdm not upgraded by default. Thus kdm failed to start. I had
to switch to gdm, update kde, kdm, switch to kdm ... not intuitive for
average user.
Nothing really important for average nerd but annoying to users not
proficient in system admin chores.
CdAB