The seats are paired; one of each pair faces backwards. All aisle seats face forward, IIRC.
Apart from initial climb and some points in the descent, you will hardly notice that a backward-facing seat's any different from normal. Some people find them more comfortable because (allegedly) of the slope of the aircraft in normal flight (which I had thought was already allowed for in the seat design).
You can theoretically watch the face of the pax sitting opposite you in the pair for the entire flight. However, each pair of seats has a fan-shaped privacy screen between them so you don't have to unless you want to. The screens can stay up for take off and landing; on the rare occasions when I've been treated to NCW I usually haven't seen the face of my opposite number until getting up to disembark.
In the centre block of a 2-4-2, the two middle seats both face backwards and are next to each other. There is no privacy screen between you here. Good for couples.