I got a couple games with her last night.
I like her. Her gun is reliable and has a long range. I killed Mei's who didn't realize they couldn't freeze me through Fortify, and Tracers who stickied me and not killing me. Statistically, I was high on damage, and I had more "damage blocked" than I have had as Reinhardt. But, I have a big problem of reloading too much. Always have, ever since the days of Goldeneye. So, with her really long reload time, it becomes an issue. Also, outside of environmental kills and maybe coordinated attacks, I found no use for her alternate fire. She does seem like she could use a little more health, as most others are saying. She feels like a defense hero with a little toughness than a tank. Fortify is great, but you're not as tough as you think.