I am totally in love with dd2's primary school, and have had the other two in different schools, so do have some points of comparison.
Because:
They are incredibly warm and loving with the children, but actually also quite firm. When a class is working, you would think the room is empty until you actually walk in, but they also seem to do loads of creative and hands-on stuff, and there is a very lively buzz. There is no uniform, and it's first names all round, for staff too, which is not what we've been used to.
Everyone looks so happy. It is of course possible that all the teachers are part of some weird cult and are feeding the children happy pills, but that aside I'm forced to assume they actually all really enjoy being there.
It is incredibly inclusive (tho' to be fair it is in quite a middle-class area, so the challenging kids are in a minority). They are very welcoming, and have an active programme of parents information sessions, coffee mornings and times set aside for you to speak to teachers informally.
The children all do really well academically, despite the apparent absence of pressure and homework. They do challenge them, but it seems to be quite subtle. But see above re. catchment area.
Not sure whether this will help or depress you, though...