At my previous airline, a LoCo from LGW, I had a purser that I didn't like very much, but her safety demos were excellent.
She always started with...
"For your own safety and those around you, we ask for your full attention while we take you through the safety features of this aircraft, so please stop talking, put your papers and books down, and remove your earphones.......
She would then look down the aircraft, and make sure that every single person was watching her - that's the whole aircraft - over 150 pax!! This often took quite a bit of time, I can remember standing at my demo position for what felt like a whole minute while she stared at a pax who was still reading.
Finally when she had all their attention, she said "Thank You" and continued with her PA
For me, it annoys me if a pax doesn't pay attention, but I have given up letting it bother me. You can lead a horse to water, but you can't make it drink! At the end of the day, I am standing right next to a door, and will help people as much as I can, but as soon as it gets the slightest bit dangerous for me, I'm down that slide!