I have actually hiked this trail a half-dozen times, with various combinations of friends and family. The hike, even in hot weather, is astounding for its diversity and beauty. If you only have one day, you can't go wrong with this hike. My first trip was at age 40, in 50 degree temperature and 50 mph winds, neither of which measures up as extreme in this locale, so check weather carefully.
I would, however, recommend other hikes in the park over the Guadalupe Peak hike for those who want to have majestic GREEN photographs. Because of the peak's southern location, only the southern faces of Hunter, Bush, Bartlett, and Shumard peaks will be seen, and these southern faces are far less photogenic than the northern faces of the range. If you want pictures that resemble the Rockies of Colorado, try the Hunter Peak trail (which will give similar relief vistas, but feature the northern faces of Guadalupe and Shumard), the Lost Peak hike, or McKittrick Canyon beyond the grotto. All of these options will still require substantial elevation gain, in excess of 2000 ft.