We have had a few patients who have had it done and lost quite a bit of weight. Most of these patients come to us because of kidney stones which they developed after having surgery. Our docs say this is very common side effect of this type procedure.
Those who have had the surgery done have to go through a lot of psychological testing as well as join a weight-loss program and successfully follow it for several months prior to surgery...they also f/u regularly with a nutritionist and fitness experts after the surgery as well.
At diagnosis, I was more overweight than you are right now, so I know where you're coming from. It is frustrating to have a lot of weight to lose, and very tempting to do something drastic to help it along. Since diagnosis, i'm down 80 lbs...still have more to go before i'm near my goal...and things have slowed quite a bit weight-loss-wise (myself included, as I tend to "hibernate" during the winter

)
Are you able to exercise? I know at first, it was very difficult for me to move around without getting short of breath...it was also embarrassing to be around others while sweaty and out of breath, but you just have to push pride aside for your health. If you are able, i'd encourage you to move around as much as possible and your stamina will improve as time goes by.
I think that even with the surgery, exercise and good nutrition would be vital in maintaining good overall health.