I like the firmness of the sofa, it's soft enough and there's more seating depth than I had expected reading through the other reviews! 
It's a great little sofa that will fit well in our den. We're lounging on it before our living room sofa arrives, and while the straight back is definitely not the long-living solution that we'll keep in our living room, we expect it'll be perfect as an additional seating and bedding option for guests.

The customer service over the phone was also very helpful and efficient!