Does this card allow roaming on China Unicom's data network in mainland China? I will bring a European phone that cannot use the 3G/4G networks of other Chinese providers.
YES. This SIM works both China Mainland and Hong Kong.
I am going to Guilin region for 10 days. Need a data package SIM card mainly to do some internet surfing, Whatsapp messaging. I don't watch video or things like that.
What SIM card do you recommend?
the SIM is best for you ,you can use it to access WhatsAPP, google, Facebook and any Apps like home:
CHINA, HONG KONG & MACAU DATA PREPAID SIM -2GB/30DAYS
Will this sim card give me coverage in Shanghai, beijing, Wuxi, Suzhou and Hangzhou?
YES. This data SIM covers all around China including Shanghai, Beijing, Wuxi, Suzhou and Hangzhou.