Well, with me it depends on what kind of immortality. Can I still commit suicide? Can I, at one point, be mortal again?
Because if no... well, I would still do it, but then it would be a sacrifice rather than a blessing.
See, I would be a scientist. Someone who can't die will, after enough time, simply know so much that he could help tremendously in any field. Although the human brain at one point will start to throw out old memories (memory capacity of the brain is still limited), with so much time you could do so much good. It would be a curse, you would at one point want to die. But I would still do it, to help.
Strange, I just saw "In Time" and right after turning my PC on, I see this thread.