I have about 1000 miles on my Sport Limited PZEV. I have only two fillups currently. My fuelly calcs say about 29mpg while my TripB that has not yet been reset says 31mpg. I do mostly commuting but did a few hundred miles road trip one weekend. I'm coming from a 2003 Civic and am happy with the Imprezas numbers so far.
To compare the same driving routines with a light footed driver:
2003 Civic 1.7L VTEC vs 2012 Impreza 2.0L
Commute: 29-31 v. 27-28
Highway: 33-35 v. 33
I hope she breaks in nicely and gets up to Civic range or better but if not the Subaru is still great.