All the mobile operators offer this device which I am sure is the same hardware with different badging and firmware (the logo when powering up etc). It is a good option as you can connect up to 5 wifi devices.
I use my iPhone for tethering, so my laptop connects bluetooth to my iPhone 4 and internet from there. However it is worth noting that when on a call the data connection does not work i.e. you cannot connect to internet whilst on the phone so no good if you need to discuss something on the web and change pages. I don't know if this is the case with other smartphones.