On the Bioware forum, if only half of them hate it, it must be pretty good.
That was my thought too. I've noticed a big backlash against ME3 from fans of the franchise over the last few months and a lot of them seem to be the same people that dislike ME2 for not being a "real" RPG, whatever that means. Since I think that ME2 was a considerably better game than ME1, I'm reasonably confident that I'm going to enjoy this game.
I just preordered at my local Gamestop just in case this Game situation affects supplies in the area and I'll pop in early next Friday to pick it up.