This is a hike that I have done dozens of times... I hike it at least once, and often several times, each summer, and it's always amazing! I prefer to hike the loop in a clockwise direction (turning left at the junction), since the grade is more moderate that way. Also, I love the way the view opens up as you contour around the hills and enter the meadows.
According to early accounts and photographs, the forests on the shore of Maligne Lake and the lower slopes of the Opal Hills had burned in a forest fire in the late 1800's; the continuous lodgepole pine forest up to the junction illustrates the typical re-growth after such an event. But as you continue ascending, you leave the lodgepole pines behind and continue through older forest that was not burned; there are some really big (by Rocky Mountain standards), old trees along the stretch of trail between the junction and where you enter the meadows.... if you are aware of how short the growing season is at that elevation, just below treeline, you will understand the majesty of these knobby evergreens.
Doing "just" the official loop trail is definitely worthwhile, but if you have more time or energy, the hike gets even better if you head up the ridge. (Follow the obvious trail that branches off after you cross the creek and ravine, just before you start heading downhill and into the forest again.) A short way up the ridge, you leave the last stunted trees behind and enter the alpine zone; in July and early August, the selection of alpine flowers up there is truly incredible. For those with even more time or energy on their hands, at the top of the ridge, it's possible to cross over to the high col at the base of Opal Peak, and from there to walk up the peak. From the col, it's almost an hour's slog up the scree but the ever-expanding views are welcome distraction!