Sim card in Okinawa

Hi,
I heard that pocket wi-fi devices don't have very good coverage in Okinawa, but I'm wondering if I might have better luck with a SIM card for my Iphone. This would be for a 2 week rental, which would include travel to more remote islands such as Ishigaki.

There would be no difference in coverage since the technology is the same.

As always, the coverage area depends on the carrier used. I am not familiar with pocket wifis, but prepaid sim cards (e.g., bmobile or econnect) use the NTT Docomo network, which seems to have good coverage in Okinawa. I hear Softbank is more problematic on some of the most remote islands (though probably not on the main island).

FYI pocket wifi is actually a receiver with SIM card that receive signal from phone company and transmit wifi for connection. Its basically you mobile wifi spot where you can connect your devices for internet.
Connectivity depend on the SIM card and quality of the pocket wifi unit itself.
Pocket wifi is reccomended if you plan to connect few devices for internet.normally you connect upto 5devices on one pocket wifi.

I heard that pocket wi-fi devices don't have very good coverage in Okinawa, but I'm wondering if I might have better luck with a SIM card for my Iphone.

Most pocket wifi are operating on Y!mobile (formerly emobile) which has LTE coverage over most of Okinawa. Prepaid cards on the other hand tend to operate on either Docomo or emobile. You'll have to know which services your pocket wifi and sim card are running on if you want to compare them, but generally they should be very similar, as both networks have LTE coverage of the main islands and 3g coverage over the water and rural spots. Difference in the devices themselves (how good their antenna/software are) may have more of an impact than the network.