If you use her shield wrong; flat out. The new shield buff is said to last 4 seconds, with a 1 second cooldown. It takes 10 seconds to recharge once fully depleted.
If you hold her shield out as you're exiting combat until it's almost empty or completely empty you are using it wrong. It works like Reinhardts shield meaning you can put it up and drop it whenever. The difference with her shield is that it comes up instantly, or near instantly. It also starts recharging immediately after the 1 second cooldown. You can literally throw it up right before you get shot to negate a barrage from a high fire rate character or heavy damage from a low fire rate character.
You only need to tap the shield button. On top of this the shield cancels her firing so that you never have to let go of left click in combat unless you need to fly out. If someone is rushing you and shooting, simply tap the shield button and fly toward them and then turn to get into cover or through a doorway. Her tackle pushes people away really far on contact. She can make a full 180 degree turn after tackling somebody and still get pretty far from them.
This is how you use the new shield.
http://imgur.com/Jsxyjdt
http://imgur.com/2A5yBTe
http://imgur.com/QiyPpTE
http://imgur.com/G0GPYuz
http://imgur.com/IZ29jZ8
http://imgur.com/VdPjNAq
http://imgur.com/0NT68j0
Full Album -
http://imgur.com/a/1wytP
If you hold her shield up outside of being focus fired by multiple character it's like playing with Widow or Hanzo and never charging your shots.
I know i'll probably be ignored but I had to make this post. I see a lot of
good players who get a lot of kills and rarely die because they're good at the game. Rarely do I see someone actually use Dva effectively. You can do good in any match with any character if your aim and reflexes are good enough. However using a character effectively is an entirely different thing.