If you only have a 3G device, or a 4G device that doesn't support the available FDD-LTE bands, you might be better off getting a China Unicom HK card instead. They have HSPA+ on 2100 MHz. Google services work fine on them.
The cards are hard or impossible to find within the HKIA transit area, so you will want to either pick it from a street retailer in HK, or order from their English webstore - http://www.cugstore.com/hk_en/. Street prices are usually cheaper.
(No affiliation, just a happy customer from a few months back. I got their "Greater China 30 Days Data SIM" because I was spending time in Macau and Hong Kong as well.)
The cards are hard or impossible to find within the HKIA transit area, so you will want to either pick it from a street retailer in HK, or order from their English webstore - http://www.cugstore.com/hk_en/. Street prices are usually cheaper.
(No affiliation, just a happy customer from a few months back. I got their "Greater China 30 Days Data SIM" because I was spending time in Macau and Hong Kong as well.)