The trail takes you down through the grass and cactus areas of the bottom of the Chisos Basin before you enter the streambed which eventually exits out of the Window. The Window is actually a pour-off or exit for water that falls in the Chisos Basin.
The streambed begins as a sand and gravel streambed but eventually turns into a gray slickrock. The window is an amazing place to look out and see the desert floor hundreds of feet below. It is also an amazing photo-op. Watch your exposure.
The reason I upped the difficulty on this trail is it is down hill on the way out and uphill on the way back when you are hot and tired and, if you left in the morning, the day is beginning to get hot. The second time I took this hike, I had a hard time enjoying the trip out because I realized every step down would be a step up on the way back.
My mileage is a little higher than others because I also took the oak springs trail which leads up the outside of the Chisos mountains and has some excellent vistas of the desert below.