Hi everyone,
I went for a holiday in Japan and decided to use M1's Data Passport as I have a mobile broadband data plan with them.
Activation was simple, but not instantaneous. I activated it via my account page on M1's website but only received SMS confirmation the next day. In view of this, you should activate it at least a day before you intend to use it.
As you're roaming on a foreign network, you'll need to turn on data roaming. M1's network lock means your SIM will only be able to connect to their roaming partner's network (Softbank in Japan).
And because my phone was in roaming mode, the "R" symbol took over the usual symbols for the data network connection (i.e. LTE, H+, etc). So I downloaded an app that would display the network type in the status bar (I'm using an Android phone).
To my disappointment, I discovered my phone could only connect at HSPA+ speeds at best even though my plan with M1 was a 4G plan. Even then, it was fast enough for me. M1's roaming agreement probably only covers up to HSPA+ speeds. For those who need LTE speeds, you may want to consider getting a data SIM once you arrive, but note you'll end up paying a lot more than $12.
My phone experienced frequent network disconnections, sometimes as long as 15 minutes. I spent the first half of my trip cursing at Softbank, thinking their network was no good. That was until I discovered that I had left the "preferred network type" (android phone) as 4G. As mentioned above, the roaming agreement probably covers up to HSPA+ connections only and the frequent disconnections were due to the phone trying to connect to 4G without success. There were no more network disconnections after I changed the "preferred network type" settings to 3G midway through my trip.
All-in-all, the speed was acceptable, given that I paid $12 as compared to $40+ to buy a data SIM. I used 1.7GB over 9 days, mainly looking at maps, browsing the web while on the shinkansen, posting to social media and tethering my phone to the laptop when the hotel's wifi slowed to a crawl every night
Is M1's data passport worth it? For Japan, probably yes, considering the high cost of a data SIM. For other countries like Malaysia and Thailand, a prepaid SIM with a data plan is the way to go.
Hope this helps