This year on both flights we had the same people sitting in front of us. As soon as the seat belt sign went off, all seats were immediately reclined, the one in front of me just as I was completing the green forms. Because of the reclined seat and the lady's hairstyle I couldn't see the screen for the films etc either. At no point did she or her husband put the seats back up until asked to do so on landing.
The same thing happened on the way back, but this time I was ready and asked them politely but firmly if they could adjust their seats so we could eat in more comfort.
I never usually recline my seats, but behind us we had two young children, who were fairly well behaved and quiet, but did keep kicking the seats when getting out to the toilet etc (which happened quite frequently). However, when they fell asleep I did recline the seat a little as they were small enough to curl up in their own seats, so no feet were sticking out.
I don't mind if people recline if they ask, and are considerate enough to put the seats back up when eating etc.
This year we were particularly cross, because these people had extra legroom anyway and were practically laying down. They got plenty of sleep, but we didn't!!