Sometimes you just need a connection from a machine for just a couple of minutes, with the current sticks you need to install all the software to get a connection.
With Mi-Fi devices simply push a button and connect - then you've got your own mini hot spot to connect multiple devices.
I managed to pick up the Huawei E583x in Australia last week and I've got to say I am really impressed doesn't matter what OS or device - if it's got Wi-fi it can connect to this device - no need any more for multiple data sticks or data plans.
Hope to see these with NZ carriers soon.
Here is a link to the Virgin Mobile one
Note they are sold locked, unlock solution is currently being worked on - hope to have my unlocked and on Vodafone here in the next few days.