Because this is the family segment, it can be hard to imagine a small car can ever have enough space, but the Civic sedan doesn't feel small inside. There is more room than in the hatchback version and we didn't have any issues at all with leg or head space, even with the taller members of my family.
The back seat also has enough space, and I had loads of room. At 161cm I can easily fit with enough space between my knees and the seat in front of me, and taller adults would also be able to fit comfortably. For a small car, that's great news.
The boot also has a surprising amount of space; 525L is more than some mid-size SUVs, although this boot is lower and not as convenient to use, there is still a load of room here. It fits the bulky CarsGuide pram, and groceries/school bags will fit, too, so there really is enough space for a family of four.