Surprisingly works very well with excellent coverage and speed (by KT Olleh). No need to worry about massive data usage, I stream HD youtube videos - even hotel room wifi has lag. Just show the email to the airport wifi counter and receive the SIM card. Options of different size card (micro/normal) and refundable (if use your phone). I used my own MIFI device (4G capable) and its easy as pop the card in and on to use.