several highly qualified surgeons will tell you that the success rate for TOS surgery (as published by them and others) is on the order of 70%. Success is defined as a 50% or more reduction in symptoms based on polling the patient. There is lots of debate as to how accurate this number is, but it is what most of the good surgeons will tell you.

i have had a first rib resection on both sides ~4 and ~7 months ago. For what its worth, i am better now, and still steadily, if slowly, improving. I am not well enough to go back to work just yet, but I am getting close. I'd probably be back by now if I didn't have two small kids and a teenager to look after, but that is just speculation since reality is that i do have the kids and am responsible for looking after them. It takes two years for the scar tissue from surgery to stabilize, so the real answer of success won't be known until then.

as for the surgery itself- very easy compared to living with TOS every day.