This diet like most will work when you work with it. Eating pre-packaged food is a good way to learn portion control. But you don't get to learn how to maintain since you are not eating real food that you have to prepare yourself.
As long as you stay on the program the Nutrisystem works but after you stop ordering their food, unless you are very careful, you will gain weight. There are better ways to lose weight that have longer term results.
Yes. The Nutrisystem Diet works by carefully controlling the calories that you take in each day and providing balanced meals. This is convenient for people who do not have time to do this for themselves but you pay extra for that convenience. If you wish you can do the same thing yourself by preplanning your own meals.