The trail in the fall is especially beautiful and secluded and the hiking temperature will be ideal. There is little on the New Jersey section that can be considered dangerous if some common sense is utilized. Snakes are rare. I've never seen a poisonous one on the trail in New Jersey but some hikers have. Treating them with respect is certainly sensible.
Bears are around but they're skittish and are seen occasionally.
Some years ago I did a little hiking on the trail in Maine, confident that in Maine, at least, I'd spot a bear. With any overnight hiking it is a good idea to bring along a light tent in case of rain. Without it the sleeping bag will probably get soaked and if the weather turns chilly this could be a serious problem. Besides, they are frequently damp and dirty. The trail, in New Jersey at least, is not enhanced one whit by their existence.