It is, but the trouble with the Simplicity is that it does not offer Visual Voice Mail, and you can only choose one bolt on.
So you would have to give up either the unlimited Web or Wi-Fi.
The people that upgraded / purchased their 3G iPhone on an 18 month contract are now up for renewal, has anyone tried to speak to O2, to say you are leaving for Orange / Tesco? Did you get any better deals?