I will give it a go for a couple of months, but I'm not really amused about having to pay £7.65 a month. O2 are such money-grabbing barstewards. Roll on November so I can go with another provider.
Well I've been with O2 since the original iPhone was released and just recently switched to Vodafone... that lasted a week and I switched again to 3. So far, it's been brilliant. Signal strength where I couldn't get any before and on their The One package, I get unlimited data and free tethering for £25 a month (sim only package).
If anyone is considering a switch to another network, PLEASE be aware that you have between 7 and 14 days cooling off period where you can switch to another network.
I ported my number from O2 to Voda and then to 3 within a period of three weeks. Don't stick with a network that's not working for you.