The class starts pretty manageably but gets rather hard after mid-semester. You'll definitely get a hang of the written language if you practice enough and do the homework. Ghazzal is sweet deep down, but likes to seem like a hard ass. But to some students in the class, she *is* a hard ass.
Right before the final, she basically told us we had to know Chapter 9 and 10 (although she told us to know the Vocab earlier on), the way it unfolded was just abominable. The amount of new material -- not just vocab -- but actual grammar, was rather unfair as I saw many students suffer because of it. I don't think she gives out A+s, since I had ~98 average score and got an A. It's a smaller department and thus probably a little more subjective / BS. Some people who clearly didn't do as well got As. It's how much effort you "look" like you're putting in, I guess.
Overall, she's a good pedagogue. Tells it like it is and is straightforward. You'll have to try to decipher her handwriting sometimes, but it's her way of pushing you to read carefully and it'll only benefit you in the end. Most of the heritage speakers can't read or write, so don't worry about them making you look bad. They speak and understand relatively well, of course. But then again, most of it is more formal Persian which they don't commonly use. In other words, you'll be fine if you've never said a word in Persian before.