Yes, the Grand Canyon is all that it's cracked up to be! I've been twice - once when I was 9 and as an adult. During the former trip, we drove in my cousins car from LA and saw other tourist sites along the way, including the Hoover Dam and Vegas. I remember it being stinking hot at 110 degrees Fahrenheit and the drive was almost unbearable, even with the AC. My younger sister screamed and cried for a good part of the trip because she was so uncomfortable. But once we arrived, I kind of forgot about the heat and was astounded by the rock formations and fantasic colors.
I went again in 2004 with my then-fiance' while we were in Vegas. We took a plane ride above it and I can say that the ride was worth it. You really get a sense of how massive the canyon is. For those of you considering a visit, the Grand Canyon will not disappoint!