This is a difficult trail if you are not prepared.
1.) DON'T go if it is hot outside. The trail is deceptive. It's all downhill until you get to the river. Once you're ready to head back, it's all uphill back to your car. As this is the desert, you will get dehydrated quickly, and the heat will just increase your dehydration faster. People have died on this trail and there are volunteers at the head of the trail to make sure everyone going down the trail is prepared. There is a water stop that volunteers stock with bottled water, but please bring your own. You will need lots of water.
2.) Don't bring your pets! There are lots of places you have to climb up/down huge boulders. There are ropes you'll need to use to belay down the rocks. Don't let your dog go through this!!
3.) If you aren't physically fit enough to climb over huge boulders, do not attempt!
Besides these three key points to keep in mind, the trail is a great experience. There are beautiful hot springs towards the end. You also get to hang out on the Colorado River once you make it to the end, complete with a fantastic view of the new Hoover Dam overpass.