The Nordic Trak is a great machine for at home exercise, but if you expect it to be just like cross-country skiing you will be disappointed. The movement is similar, but definately not the same. Remember, any outdoor activity that you try and duplicate on a stationary machine indoors will not be the same.
All this said, the NordicTrak is one of the best quality machines you can get for at home exercising. It is a very well made piece of equipment and should last a long time. It exercises all the large muscle groups (legs and arms) and gives a great cardiovascular workout. The movement is smooth and low-impact so even people with joint problems can do it.
Just don't expect the exhiliration of real skiing!