I have been to the Arcadia location quite a few times and this is what I liked better & worse about this location.
Better:
There is definitely more parking at this location.
This location is bigger, so they have more seating available.
Worse:
I think the ambiance of the Arcadia location is better.
The service & quality of food at both locations is consistant I would say. See my review on the food & service on the review section of the other Postino!