Looks like a decent option for those on Optus prepaid and travelling overseas to those 5 countries.
Or buy an Optus sim which is regularly on special at Coles/Australia Post/Optus.
Data only lasts for 5 days though.
You need to be on the Optus Epic Data or Epic Vaule plans (so can't add it to the Daily Plus or Long Expiry plans).
For some reason it is actually cheaper than buying data to use in Australia where $20 get you 3.5GB to use over 7 days - go figure.
Ridiculous that the post-paid option is still $10/day for 100mb.