I had always quite liked David, and felt that his characterization as 80% a pretty easy-going pleasant guy who was nonetheless capable of Lawrentian rages (cf the tree house of lurve, and Peep's affair with the obnoxious Jude during her AS levels) was well done.
But I think the way he behaved, aided and abetted by Jill, about the move, was poor. Yes, we can say that really a farmer wouldn't have wanted to move in the first place so it was an unconvincing story line anyway, but still - he said they would, and then unilaterally decided they weren't, and didn't really acknowledge how badly he was treating Ruth about it all. Ok, fair enough 'I'm an Archer and I belong at Brookfield', if that's how you feel - but Ruth is not an Archer, and her place in all of that was very unfair.
I also think he's been a dick about the whole Heather thing - always telling her to wait and not drive yet, and how hard it is for him on the farm (which I'm sure it is, but it's also hard if your mother is rapidly failing at the other end of the country, as opposed to making you a cottage pie 5 yards away!). His argument about her not coming to live at Brookfield was:
maybe she won't want to
maybe she won't want you doing the personal care
well, ok, MAYBE SHE'LL DIE ON THE WAY AND THEN HOW WILL YOU FEEL?
Which I felt was poor.