At the end of the beta I had 80% winrate with her after 100 something games played and some of them were throws because of my guys playing some random heroes like Genji that they don't understand.

I guess the reason she's not popular is because she's not very easy to play (not just skill). I find that she's best paired with Winston (at least in pub play) who can go in and constantly charge you up, then bail out (with your 400 hp shield + his shield he'll live long enough to get out with the jump ability). I also think that many people play her wrong by playing too passive with her and using her incorrectly in 1v1. From my experience sitting on the laser 24/7 isn't a good thing in 1v1 against fast heroes like Lucio, you should switch between laser and alt fire while jumping like crazy because it doesn't affect your aim that much with her.

My favorite part about her is the sound. The weapon's sound becomes louder and noisier the more you charge the weapon and that sound that you hear when someone goes in and takes full damage with your shield on them is just awesome. Her damage is disgusting when charged and you can easily 2 vs 1 people because almost everyone underestimates Zarya. She's also very good against Mcree because her shield makes you immune to stuns, etc.

My only issue with her is that people don't really know when they have your shield on them (it's just a little glow on the sides of your screen, you'll almost never notice this if you're in combat). They should add it on the side of the crosshair just like how Mercy's healing / damage boost indicator works. It's not a big deal because it's up to you to land proper shields at the right time (they only last 2 seconds anyway), but being able to see the shield somewhere on the screen would be really nice.

I bet many people don't know that her shield can save you from 99999999999999999 burst damage, it will simply destroy the shield and not touch your health. Very often I just sit in DVA ults and pop my shield right before the explosion to get 50% charge just from that (or 100% if some friendly is around me that I can shield). Her self shield is on 10 seconds cooldown with 200 hp and the friendly one is 400 hp 8 sec CD. Both shields have a 2 second duration so you need to time them well. Wish her shield had 8 seconds as well to match the other shield : /