Jiuzhaigou is a picturesque place without doubt, but we will NOT recommend it as one of China's top destinations for independent backpackers.
First, the entrance ticket Y310 is too expensive. Secondly, the place is so crowded with Chinese tourists in holidays, they are very undisciplined and usually huddle and chat everywhere. The noise murders the natural beauty.
A slight update: from May 16,2007 on, "free sightseeing bus for the 2nd entry" policy is ineffective for individual tourists. Visitors who buy a 2-day entry ticket should pay for the sightseeing bus twice. The new policy will come into effect for group tourists guided by travel agencies from Jul.26, 2007 on.