It's too much for people to get used to new netcode and new weapons at the same time. I really think that Goose needs to focus on balancing the weapons more, i think that the weapon changes are the biggest problem in beta 6.5, more balance is definitely needed. Smoke grenades do not cause me any probs, and I think they really add to gameplay. There are other little niggling problems, but i wont go into that right now. Yes, the new NVG's total ruin people's FPS, and border on the line of completely pointless.
Guns shoot too much off-target.
Makes it dull. Smoke grenates slows the game down. The smoke grenades lag people to hell and my ping has actually gone up. The guns aim is so horribly messed up that aiming at a while will produce shots within a 10 ft radius. The game just does not deserve to be played.