Oh, and it cheats you out of wins by giving the opposition penalties when all you're doing is rucking normally.
Seriously, I was 29-23 up with Samoa against France in the WC quarter final at 80 minutes when the game decided Yachvili could run straight through ALL of my players and score a try under the posts, despite my fullback tackling him. When I checked the replay, I saw that my tackler moved to the side in mid-air to avoid him.
Seriously, if you haven't bought this game already, don't bother, it's like a more crappy version of Rugby '08.