I used Easton's Tracer nocks last year for the first time and they worked fine.

The pro's are:
Easier to follow your arrow in flight
Easier to find your arrow after the shot
Pretty cool for video (if you video hunts)

The con's are:
They are expensive (about $10 per nock)
There is a chance they won't work (but they still work as a nock)
They make achieving a higher FOC slightly more difficult

Overall they are a nice little accessory. If you don't have a problem shelling out the dough for them they are worth it. If the price seems steep you're probably better off sticking with a traditional nock. They are not going to make or break any hunt.