Works well locally, but not when roaming
I bought a $14 tourist SIM. The SIM card worked well in Singapore, but only worked periodically in Malaysia. I was unable to contact their support, as the SIM wasn't working. They offer no online support. I ended up talking to someone from the broadband team online, but they said they can't help and the only solution is to call the number (which I couldn't call). There was no obvious reason why it wasn't working, as it would randomly happen in different locations. The data speed was also much slower in Malaysia.