I wrote one this year. It was either that or (a) confine myself to Dear X Love from Us or (b) subject the poor innocents to my ever-deteriorating handwriting. I think I did okay. I didn't refer to myself in the third person. I told them DH hadn't really done anything this year apart from remain married to me. I told them DD had learned to swim, albeit in a manner reminiscent of barely controlled drowning, and included a picture of DD looking quite appealling, and our kittens looking far more innocent than they actually are.
I actually wanted to send 2 sides of kitten pictures with a scribbled note 'DD and DH both fine', but chickened out.