|I have taken it and for me it seems like I build up a tolerance to it very quickly. I had to take a good healthy dose (450 mg) to get pain relief, and at first it did help quite a bit.
For side effects, like any drug there are initial side effects that go away (diziness, etc). Persistent side effects I experienced were constipation and really watery, dry eyes. I finally decided the minimal pain relief i was getting didn't outway the side effects for ME.