Hi Stu
Personally I love it. I've had it for around 10 months now and so far it's been great. Once I had to reinstall the Nike+ Connect software but that could have been my pc and only took about 15 mins anyway. The only other negative is that it doesn't pick up the GPS quickly if you haven't connected the watch to your pc recently (it updates the GPS data everytime you sync it to your computer so it's best to do it regularly from what I have found).
Otherwise I love it. I use it for my interval training as well as normal runs (it has an interval & a lap function on it) and I recently got the heart rate monitor that works with the Nike+ products. So far so good on that front too.
My opinion should be taken with a pinch of salt as this is the only GPS watch i've ever used. I researched a fair amount before buying and the consensus amongst the more serious runners seems to be that the Garmin is better, more accurate and generally more durable.
Im not a serious runner but i do run 35-50 miles a week and the Nike has never let me down.
Hope this helps. Let me know if you have any specific questoins about it
Chris