Yes and No. It all depends on the factors of age, weight, and degree of fitness. While walking is never bad for you its benefits are very different based on the individual. A basically sedentary person with a low degree of physical fitness may benefit greatly from a good walk. While a person in fairly good shape may barely experience a rise in heart rate with walking. Aerobic exercise is fine and is a good supplement to ones overall well being, but in terms of weight loss and it being permanent, building lean muscle through resistance training is the best answer for most. Also with building more muscle your body burns fat and calories constantly, unlike aerobic excercise that once you stop so does your calorie burning, which in turn gives you a little more leeway in diet once you have established better health.
Aslan, not knowing you I can only give an opinion about your situation based on what I see and hear about in the majority of those trying to lose weight. Most of those who find that nothing works for losing weight, short of those with medical issues such as thyroid problems, are not actually pursuing it with the best outlook. Good health and fitness is not something that comes easily, or quickly especially if you are very out of shape. Just like card counting is not a get rich quick scheme, good health should be thought of similarly, long term and not just as I need to lose X amount of weight. Good health is a lifestyle and doesn't end when you lose a few unwanted pounds. Thats why adopting a healthy workout and diet plan should be realistic. One that you can actually live with everyday, not something that deprives you to the point its never going to be an everyday part of your life.
I am a very busy person, and have in the past let my health and weight suffer because of it at times. But I also realize that my quality of life in general is better off when I take care of myself. I am a bit extreme in my fitness now because I generally do enjoy it, but being healthy need not be that way for everybody. Slow and steady works too, as long as it becomes a way of life there is no race in being healthy.