PCOS & Metformin

I was diagnosed with PCOS 4-5 years ago & hubby & I have been TTC for about 18 month (naturally). I just got a referral to see an ob-gyn, who has prescribed metformin to help with insulin resistance. I start taking it tomorrow. Just wondered what are others' experiences with it and is there anything I should know? My doc was pretty light on the details, he pretty much just said "it will help"?!