Modder Fakefactory released the first screenshots of the new Alyx model. Those are "Very Early Beta", so they only give a brief impression in the current state of development and are not necessarily comparable to the final graphics of the modification.
The biggest change is the new, additional Alyx model that isn't inspired by supermodel Adriana Lima (who had been a controversial matter among Half-Life 2 fans) anymore. Fakefactory now tries to copy the original real-life model for Alyx, the actress Jamil Mullen, who spent several days in a studio for motion capturing purposes when Half-Life 2 was developed. Below you can find a direct comparison between the two HD Alyx models; just click on the names to switch between the pictures.