This is an outstanding hike. I first did the hike in January 2007, and I decided to give it a go yesterday, March 20, 2014. The trail has changed somewhat with the addition of some switchbacks that weren't there in the past. The final ascent is also a bit easier.
It took me two hours to reach the summit. My GPS shows I was moving 1 hour and 39 minutes which means I was taking photos or I was stopping to get my breathing back in line.
Daniel's review has a great description. The only thing I can add is the photo showing the dirt trail that you have to take to the back side of the retention basin to get to the Sloan Canyon NCA signs and the Black Mountain trailhead sign. If you cross the spillway of the retention basin, you haven't gone far enough.
The way back was much easier for me because I find coming downhill easier. I wear hiking boots with good tread and I tend to dig in better.
One of the new views from the summit is to look to the south and see the three towers to the newly opened Ivanpah Solar Electric project. You can see the gleam off the towers along the trail when you get enough altitude. You can see all three well from the summit.
Take a look at the solar plants in the Eldorado Valley also. The views from the top are great.
Happy hiking!