Love or hate it, you have to admit, it's convenient! The large parking lots bring large crowds. Regardless, this is a great hike. If crowds get you down try the Circumference Trail. (claimed one of the best wildflower shows in Arizona).
Okay so your heart is set on the summit. This is an old horse trail. Some of the railings are still in place up near the mile mark. The trail was mainly used for means to travel to an old mine. You can forget exploring that area as it is off limits. So stay on the trail and keep out of trouble! Plenty of restrooms are available in the parking areas. It's great to wash your face off after a hike in the summer heat.
The trail starts out with a few switchbacks. A wide trail handles the crowds fairly well. At times it gets extremely crowed. Then there are times you luck out and a beautiful day will go by with only a few visitors. Conversations of how Piestewa compares to Camelback is often heard in passing. Camelback while statistically more challenging is smoother. An extra 100 feet of elevation, two steep handrail sections and a few stretches through boulder fields gives it the "tougher" nod. The footing on Piestewa is typically more jagged yet generally no steeper than a staircase.
Several benches along the way provide comfort. Passing the 0.25 mile marker you are in the midst of switchbacks. Between the 0.45 and the 0.6 mile marks the trail flattens out. The Circumference Trail spurs off to the left and then down away at the half way point 0.6 miles. Continue on up the next series of switchbacks that start immediately after the 0.6 mile marker. The second section of flattened trail opens up after passing the 0.75 mile marker. Enjoy the stroll and relax as the nasty sections are yet to come. The trail goes in and out of the contours with minor elevation gain for a short distance. Welcome to never ending switchbacks. It's something like thirteen in a row. The first being the least forgiving as it is steep and the footing is rather loose. After that it's not too bad footing wise. The third takes you up to a popular bench. After the fourth switchback comes the largest step with exception near the summit. ( now gone, this trail receives a lot of volunteer maintenance ) On Camelback these are the kind of long legged steps you battle over and over again. More steep slopes are encountered passing the one mile mark. Though it's nothing to worry about as the steps are small and close together. Just like a staircase.
Okay it's on to the summit. Believe it or not, only a small percentage of the crowd makes it up to the official summit. Most are satisfied with the larger area just a few yards shy of the peak. It's fun to look around and see the city from a birds eye view. Personally I prefer the shear drop off from Camelbacks summit which adds a real sense of elevation! Piestewa Peak is a nice alternative when you can't get into the Camelback parking lot!
This is a preserve. Taking home rocks or even moving them is prohibited. Leave the wildflowers in place. Only park in designated areas. Do not cut switchbacks. Over the years I have seen rangers hand out tickets for all of the above. An illegal parking ticket really puts a damper on the ride home. I myself have been tempted to follow an old obviously blocked trail that cuts up the dreaded switchbacks. Forget it, it's stupid and just isn't worth it period.
Over the years I have met many rangers on the trail. They are friendly, helpful and do a great job.
 2014 - 17 years later I'm not sure on my source. Met a man named John that farmed in the area back in the 60's. He said the city paid them 5k to construct the trail to the top in 1965. I asked if it was originally a mining trail that ended near the horse rails and he said no. I asked if it was built for recreation and he said yes. Also stated that burros were used rather than horses to build the trail. People did take horses up often back in the day.
Check out the Official Route and Triplogs.