This product is ideal for me as a novice runner, training for a marathon (for the first time) later this year. I've checked the accuracy of the measurements (out of the box) and it is within 0.03mile over 2 miles, which is good enough for me. You can callibrate the sports band for either walking or runiing, which is a useful feature.
One point to note: It wasn't obvious to me, having not used this product before that there are two parts to it. I also think it isn't clear in the instructions. There is a sensor (eliptical shaped plastic with apple and nike swoosh on it) and there is the wristband and display (as shown in the image). I initially thought that all you need was the wristband. The sensor is in the plastic box at the bottom, you have to pop it out. I also then bought a sensor pouch (which sensor is placed in) that you attach to your trainers using your shoe laces. You would have thought would be a complimentary sale for this product but, I discovered that for myself. Apart from that gripe a great value for money product and the graphs produced in the Nike + area are intuitive and a good running motivator.