Thankfully, for the most part. Name, position, number, college, hometown and state (not age).
If changed to QB, you can edit their style/stance.
All ratings can be edited (thankfully, because I'm looking at HB's with Spd in the 50's).
Player traits are fully editable too.
There is a TON of player generated junk (or at least more than enough to "craft" some real life UDFA with potential for each class that didn't make the import cut). While race/height/weight can't be changed, the ability to change position allows for mixing/matching for those willing to take the time.
It's not perfect, height/weight and age editing would have been great, but being able to edit anyone on any team (FA's too) without controlling them offers flexibility that hasn't existed previously. The auto generated faces look better than I thought they would.
Good luck