I just installed 671 (was holding on to 655 and it seems for a good reason).
During the install process it asked me to select the directory for the old idea version if I wanted to import the settings. I selected 'C:\idea'.
After it started the installation process it came up with an error 'C:\idea\%IDEA_HOME%\config is not a valid directory' or something like that, and another error that it could not remove that directory.
I then looked at C:\idea and saw that it was empty except for a directory with the name '%IDEA_HOME%' which had a config directory in it, but that was empty.
Now all my configuration is gone... not a good experience...