based on what i've seen, i think she's perfectly balance agent aside from her ultimate.
People have been talking about the type of agent she is, but I think she's kinda perfect for what a new agent should do- which is shift the meta a bit.
The wall I think is the real key, because she has a real chance to fight a util dump execute. Wall goes up, she pops flash, fight the entry.
Considering the time it takes for the wall to go up, you can definitely have 2-3 people go on site with the entry duelist if the team is coordinated.
As for her ult I'm assuming it just locks whatever gun you're currently holding, so I assume the counterplay would be to swap to your sidearm as the ult pops and swap back to your primary (I'm just assuming). Of course that leads to gun downtime but it is an ult after all- it should provide a reasonable advantage at least for a moment.