I had some time to play her last night for about two hours. I am loving the new mechanics she brings to the game. We were on Trainyard at the 2nd objective and my teams Vassili who was in the warehouse window went down to a Fragger. I shot him through the window on the second floor and he killed the Fragger who had passed him by without gibbing. 
The REVIVR is amazing and it makes playing medic a lot more fun imho. I was topping the leaderboard with 4-5 kills when 2nd had 30+ kills. I was getting the 20 revives award almost every single match played. Revive sprees were flying fast.
I have had no issue with using the machine pistol has a primary. I was focusing on being a medic and practicing with the REVIVR for most of those games, but when an enemy got close the MP worked wonders. Particularly good after you soften an enemy with the REVIVR at range and finish them when they close.