I have not gotten the surgery yet, however I have not hidden my decision with anyone. With that being said, I am an extremely open person in general. Anybody that knows me understands that, what you see, is what you get. 95% of the people that I have told have been overly supportive and can't wait for me to be healthy again. Then there are a select few people that have never struggled with weight their entire life and tell me I should try a diet. I usually say back to them, "No Kidding, you should be my doctor, cause that might just work." They typically get the point rather quickly that they sound pretty silly.
Like others have said though, the decision should be based on the type of person you are. If you are the type of person that doesn't divulge much about yourself regularly, you will probably keep it quiet. However, If you are like me, the neighbors brothers dog knows I'm getting WLS.