DISCLAIMER: This is IGN official gameplay, Epic versus IGN's people. Covered by IGN on their official YT channel. This is (obviously) NOT leaked/torrent gameplay. I am just sharing it here.
That being said, so far looks really good, if you watch the HUD, you can tell that this is from the final release version, it's different than what appears in earlier coverage. This is spectated from different players' perspectives and it actually makes me believe this mode could work in a competitive setting. I'm not sure how they were changing up the perspectives, might just be some slick editing on IGN's part, don't think this is someone spectating, as the match was full 5v5 and they show the scoreboard, maybe Epic/PCF modified the spectate 'mode' and made it so you can spectate without being actually in the match (As it stands, in GoW3, if you want to host a tournament and stream it, it would be 4v4 as otherwise the matches would be uneven in the number of actual players). Overall the mode looks amazing.