What kind of tablet do you have? Something that takes normal sized SIMs or micro-SIMs?
Beware that not all Three prepaid sims are the same. There are many different types of prepaid Three sims available, and they're all different in terms of initial cost, call charges, data charges, etc. If you're after a specific one, I would recommend getting one from the airport Three shop, as they speak English(better than the ones in the local areas), and seem to have the biggest variety of stock I've seen. Its true that you can get Three sims at many convenience stores and at other Three shops around HK, but most convenience stores only seem to sell the stock standard Three sim, "3G Super Value Monthly Fee Rechargeable SIM Card" (
three.com.hk 3G) which has higher charges(for data/call) than the one I ended up buying, the "3G Rechargeable SIM Card for iPad"(
three.com.hk 3G).
Depends on your usage patterns of course, each different SIM has its pros and cons. The "3G Rechargeable SIM Card for iPad" has higher initial starting cost($198), of which $18 goes to your monthly charge, and the leftover $180 goes towards costs for SMS/Voice calls, and a monthly cap of $168 a month for data ie. you can use as much data as you want for $168. This also comes in micro-sim form, so goes straight into your iPad2, or iPhone 4(or 4s). Even though it says its for iPad, you can stick it in your iphone and use it for calls as well(afaik, its the cheapest call costs too...)
The standard "3G Super Value Monthly Fee Rechargeable SIM Card" costs $98 to buy, has no monthly cost, but has higher voice/sms costs, and a higher monthly data cap of $388. I think this comes in normal sized SIM(which you can get cut down to micro-sim if needed). So if you use a lot of data, go for the "3G Rechargeable SIM Card for iPad" as that has a much lower data cap cost.
In terms of procuring the actual SIM card, if you want the "3G Rechargeable SIM Card for iPad", I would advise getting it from the airport Three shop, its on the departures level, right around the middle(counter A on one end, H on the other, think the shop is around counters F or G), on the end closest to the departure gates. When you land, obviously, you'll be on the arrivals level, so take an escalator to the departures level and go from there. I was trying to get another one for my gf while in HK and had trouble getting it from other Three shops in HK, let alone convenience stores like 7-11. From what was explained to me, most locals don't use prepaid sim cards, so they don't usually stock that specific product at the Three shops around HK. In fact, they didn't even know about it, until I pointed it out on their website. If you're happy with the stock standard Three sim card, should be able to buy at 7-11, etc...
Hope that helps.
