I had a bypass almost a year ago. I have since lost over 8 stone pretty easily, however, I am going through a difficult time with weak muscles and now hypoglycaemia. It's not an easy option, and requuires excellent compliance with vitamins and diet choices for the long term, and I would say that if you don't have the commitment to that, the surgery could cause more problems than it solves.
I am going to post separately about what's been happening with me lately if anyone is interested.
Rx