Has anyone used the Nike+ Sensor with the ipod?

I am interested to know how accurate it is?

I am looking for a way just to track pace when I am running outside so I can get a better idea of what pace I am really running before the end of the run when I see how long it took.

I have looked at some of the GPS watches but they are too big and bulky for what I really want to use them for.

Thanks!