Don't listen to anyone telling you not to do this because it's too crowded, their's censorship, and its unsafe. It's great! The same as any country or city.
I am an introvert, I get VERY anxious in tight crowds and I had a blast. I am also picky with food and didn't have an issue. The other people in our group who loved to party and try new food such as rabbit head or weird things on sticks didn't have any problem finding what they were looking for either. China is for everyone. Do not be intimidated or scared. Everyone was friendly. I'm high maintenance and aside from the squat toilets nothing fazed me. Even the giant spiders mind their own business.
Before your trip - most people didn't get shots and were fine. I got an anti-diarrhea vaccine which helped greatly. I am susceptible to food poisoning and I could tell when I had it twice from trying some new stuff but it was okay because of the vaccine. Pack or purchase toilet paper as it's not available in restrooms. Squat toilets only outside of touristy bits and your hotel. Get used to people taking your photo. It's not weird they aren't used to seeing white or colored people. Oh and save all your shopping for Shanghai - I promise the millions of fans, t-shirts, tea, and magnets you go by through the two weeks will all be in Shanghai. That was our shared regret on the trip!
Price - worth it. Yes it's a huge chunk of money but this is definitely one of the best Contiki's I've been on and a big culture shock if you've done a few European ones and need a spot to explore. I am a shopaholic and only spent $300 on my souvenirs. Food, drinking, and Contiki optionals cost $400 on top of that. Very inexpensive once you pay for the trip and plane tickets.
Food - whatever you want. I will say the included meals are western Chinese food but large quantities. But my trip manager had great recommendations for foodies. Whether you wanted authentic Chinese food, weird things, or some good ol' pizza she had you covered.
Optionals - do them! Loved all of them. I skipped the cooking class and had a better time exploring Chengdu but the people that went had great fun. River cruise was great to see Shanghai by night. Paid an extra $20CAD to escape the crowds and it was worth it.
Accommodation - Hard beds. This is how Asians sleep. Get use to laying on what feels like a wood box with a cloth draped over it. Aside from that I found everything great.
Partying - They don't dance but that didn't stop us from dancing. They also love to free pour. I'm a small girl but two drinks had me hammered. They do full glass of liquor and splash of sprite. Girls be advised only squat toilets so be careful not to step in them when you're drunk!!
Transportation - Internal flights were great - food was weird so pack your own. Even a local next to me on my flight was like WTF am I eating? Train was a solid miss for me but that's because I'm an introvert and hate tight spaces. I just slept through it. (I had my own room for the rest of the trip)
Overall, whether you're introverted, extroverted, partier, or explorer, young or old you will meet awesome people like yourself and China has something for everyone. It was all fantastic. My favorite spot was the 798 district. Great spot to explore, shop and take the BEST Instagram posts.