Just how hard is MATH 18 (Linear Algebra)?

I've heard countless horror stories on how much people struggled with MATH 18 and I'm a little anxious to take it. The SETs results show that the average grade received tends to hover around a C. I got below average grades in 20A and 20B—and struggled immensely—so that doesn't make me hopeful.

I've watched a handful of videos from the 3Blue1Brown Linear Algebra playlist and didn't find the concepts very difficult to grasp, but I don't think that's any indication I will have an easier time. How hard would this class be for someone who has historically struggled with math?