Didn't the trailer have a disclaimer about this "not being the finished product" or "work in progress"?
Besides, for those who don't want to purchase it, there's other means of playing it. Who is really going to refuse to at least try the game, given the opportunity? There's plenty of free trials for the Gamefly rental service. Redbox might have it. You could borrow it from a friend who bought it.
Some games are going to get mediocre reviews and there will still be fans who support it 100%, and vice versa. I say you need to give it a shot before you just accept someone's opinion.