The way you (and all these other ungrateful little kids) are acting is like they've totally destroyed the game and changed it completely. The gameplay is literally the exact same, the only difference being is that they've added somethings you can toggle off and on.
Nothing in it is a 'gimmick', but something that adds to the game, making it more enjoyable to those who aren't completely serious competitive players. Killcams have proven to have a lot of hilarious results, in both TF2 and DoD:S. Achievements are for those who want to... you know... maybe have fun. Stats are probably the only close thing to a "gimmick" in this update, but even those are just for fun. People were even complaining because the scoreboard wasn't transparent enough, and they couldn't see the action of the game behind the scoreboard.
Every single person whining about the update is overreacting and extremely ungrateful. Be thankful they even touched the game after all these years (with nothing but little, little bug fixes), even if it's because of Mac coming to Steam.
PS: Hidden Path did most of the work on this update, not Valve. It's another case of Valve actually giving a small indie developer a chance to do something, and they did something good. Give them a break.