It probably gets 95% of the calls right. FIFA says 99.3% but I don’t think so. Still, if it didn’t exist everyone would be crying to implement technology like they did before. Think of all the goals/no goals that have been rightfully overturned. Even if there are some horrible calls sometimes, the good calls outweigh the bad ones.
With how much they look at the footage with all those angles, it should be 100%. Theres way too many controversial decisions made for what the technology is. It’s plain incompetence in officiating.