I admit to smoking in my late teens and early 20's whilst studying for exams many years ago. I then started a long term sore throat and cough, which just would not go away. I stopped instantly and now have a total aversion to smoke, it makes me breathless, and causes coughing, and also gives me pains in my chest, due to having a serious illness last year. A friend of mine's husband smoked a lot, and he developed a rare form of mouth cancer, which he thought was due to smoking, he quit just like that, no devices, patches or anything. He found it was not due to smoking but will never go back to it. Just shows it can be done!
It should be more effective than any other method however it should also prove to be the most difficult way to stop as well because one would not be allowing his body enough time to adjust properly to the immediate chemical difference that is sure to result in the cold turkey method but it should be more effective by far if one can endure it.
It may take time to quit smoking, because if you just stop you probably are more likely going to go back and start smoking again, because you have developed a habit in which you have to smoke and it is not that easy to just quit smokin like that so disagree.