How effective is the GERD surgery in reducing symptoms?

Very effective. Surgery is very effective. But frequently your gerd symptoms of heartburn may get replaced by gas bloating symptoms. Please discuss those symptoms in detail with the surgeon before saying yes to surgery. Surgery is an excellent option if your heartburn symptoms are really frequent and bad.
Very effective. Approximately 95% of patients who undergo fundoplication for gerd report significant reduction in their symptoms. A useful test to perform before surgery is a 24-hour pH study, which helps correlate one's symptoms with acid presence in the esophagus. This is especially helpful for people with atypical symptoms.