My son has lived in Saco which is right next door to Biddeford, he and his significant other love it there and when I go up to visit them I agree. My parents were in a nursing home in Biddeford for about 5 years, so I was a frequent visitor as was my brother who would come up from Nashville each summer for a couple of weeks to visit and rent a place to stay. I haven't "lived" in Biddeford, but I have done a great deal more than "drive through".
Biddeford is an older mill town. It is situated south of Portland, but within very easy commute distance. The mill economy failed some years ago and the typical red brick mills that lined the Saco River stood empty and forlorn for years and jobs were scarece and property in town declined. Like all mill towns it had and has a surplus of tenement buildings in town and even single family homes in the center of town have very small yards. Saco sits next to Biddeford, connected by a bridge, (mini version of Minniapolis and St Paul--they really merge. Saco is a little more upscale than Biddeford, and has some lovely old Victorian Homes and lots of new developments--the type that families like to go drive by at Xmas to see the way people light up their houses.
Because of the mill economy, the area had lots of French-Canadian immigrants come down to work in the mills and the French Canadian Culture is still apparent and after all the years of discrimination, proudly celebrated in the Franco-American festival with Kermit "The Frog" as the grand marshal.
The economy of Biddeford/Saco is on the uptick; and there is a good energy and lots of community pride. My son's significant other, who is Maine born and raised, highly recommends Saco to me when I finally get to move up there. Of the towns she has lived in (mid coastal), she likes it the best!
As you may have discerned there is a divide in Maine between northern Maine and southern Maine; I don't hear it so much from those in Southern Maine, but many up north love to insult and disparage the south as it is culturally different.
I would encourage you to consider Saco/Biddeford and I think it would be a great place for a young couple "from away". It is not an exciting place--but for entertainment and cultural events etc. Portland is just 20 mins or so up the road.
Good Luck.