Just back from Jiuzhaigou and I have to say the photos DO show the real thing. I spent 3 full days in the valley and walked my legs off. Definitely worth spending more than one day. If you have to cut short, give the Rize Valley a miss as the seasonal lakes are empty right now.
Instead of eating at the overpriced Visitor Centre walk up the hill a wee way, or wait until you get down to Shuzheng Village and eat Tibetan food. Instead of 50-80 for a Chinese meal I had a delicious yak sandwich for 25 RMB.
I strongly recommend the new Eco-tourism venture whereby you travel up the un-touristed Zahru Valley, visit Zahru Village and then hike up into a former yak meadow, where you camp for the night. Good quality camping equipment is provided and the guides speak excellent English.