I tried Symmetra a little last night on the PTR.
1- Longer range on primary, it's not huge but it definitely feels better. She's a lot more dangerous when fighting on point as her beam will easily latch on anyone nearby.
2- Her barrier is pretty cool, it seems to have decent health, moves pretty fast, and has a long range. It's hard to use it well on PTR as people in QP are not coordinated at as a team at all. I think it will end up being pretty good ability.
3- Shield generator is bugged. If you die you get the shield back, makes evaluating it difficult...75 shield is a lot though. It seems to last forever too...a 225HP Tracer is a bitch.
4- Sentries, 6 charge and shorter cooldown...man are those fun to use now. It totally changes how she plays, and where to put them. For example on Hanamura defense. At startup rather than to put them at the choke door like I usually do, or in the room to the left. I put them closer to the spawn, under the pass and behind the column in the middle of the path leading to the door.
They killed 2 people, and we fought a little and stopped their initial rush there before they reached the door...don't think they expected the sentries to be there. Then I moved the sentries to their usual place, slowed them down by about 30-40 seconds before they even reached the choke. And I had time to place all 6 there before they were really pushing. Probably won't work all the time, since at some point people will expect them to be there...but it was a nice surprised and it worked.
Continued playing all the way to point B, and was able to put in 1 spot before they got to point b, then I kept fighting on point B, placing the sentries in different place for almost each of their push.
We won, I had over 30 eliminations and close to 20 were objective eliminations. My sentries and primary attack was wrecking havoc on the other team.
It was quite a blast.
I wasn't very successful using her on attack, the shield generator is nice, but placing sentries effectively on attack is a bit difficult, especially on point A since you're behind a choke point usually and the defending team just won't come to anywhere you might be able to put your sentries down.
It was a bit more effective if you get past the choke because the defending team will try to retake it, and will have to go past your sentries. It still wasn't extremely effective. On point B it was a bit better since team defend a bit more aggressively, so it was easier to deny them a few areas with sentries.
Overall, I still think she's better on defense, but can now defend the entire maps. She might be more viable on attack, but I still don't think she's that good.
Still it's very fun to melt people.