Not great
I previously purchased a 15 day Asia esim and it worked great, I then purchased a Japan 5GB for 7 days and it has been awful. I always try to use wifi where possible but often this doesn’t work so I turn it off and use my data but it rarely works. Also in 3 days I have used 50% of my data already. My previous 5GB for 15 days lasted the entire 15 days. I had no issues using the data and switching to wifi when needed. Very disappointed this time around. Also always takes a bit of fiddling when activating it