I can't help but think she would have terrible depth perception with just one eye.

However, that make it even more awesome that she is an excellent sniper.

In real life snipers have a partner that will tell him things that he can't tell with his scope alone, like range.

The picture shows his partner has a range finder. Which is something you wouldn't be able to have built into a sniper's scope.

To tell range you need depth perception, which requires two (or more) eyes.

So, for her to be able to snipe with only one eye and no partner means she is truly gifted.