The BioWare Social Network has a post from BioWare's Chris Priestly on a problem some users are having importing character faces from Mass Effect 1 or 2 into Mass Effect 3 (thanks Eurogamer). They are still working on this, but in the meantime, endorse a user-created workaround:

We are aware that some players are having issues importing the faces of characters from Mass Effect 1 or Mass Effect 2 into Mass Effect 3. The issue is likely in how faces were detected when imported from Mass Effect 1 into Mass Effect 2, and we’re working on the best way to correct it for affected players.

As our teams work hard to address the importing of face codes we would like to call out a fan made tool that may be able to help PC users in the short term:

Mass Effect Tools

And detailed instruction from a fan on how to use them here.