Yes, I own one and it is a good starter's GPS watch. Mine is very accurate.
The higher end ones from Garmin and the like do sometimes offer more features (I hear they have some limited mapping capabilities so you can pull a basic map up on the watch; can give you more feedback on the run like whether to slow down or speed up based on vibrations, take your pulse rate etc.) but the Nike+ does all the basics.
I like mine. It tracks my distance, speed and route (which is uploaded after the run and is viewed on Googlemaps) and those are the main things I need. It also tells the time
The only drawback I have had is that sometimes you have to wait a little to pick up a signal. This is most often a problem when you start running next to high buildings. Or if you start running in a different country (which I do from time-to-time!).
On the accuracy issue, they are most probably referring to the in-shoe sensor which you can use to track runs indoors. This is not as accurate as the GPS.