Just gone for the 64gb 900minute 18month contract with vodafone. I persoanlly thought their deals were quite good.
I currently pay £20/month for a rolling 30 day contract with 600 minutes, I know you can get better deals, but I've previous had a very bad experience with one of the less established provides.
If I purchased the iphone out right, over 18 months it would have cost £1059
On an 18month contracy with 900 minutes it comes in at £988, this includes a £59 discuount for pre ordering today. Oddly it's cheaper over the lenght of the contract to take 900 minutes as opposed to 600!
This seems like a reaonable deal to me. By signing up to a contract I save £71, gain visual voice mail and spread the cost of the hardware over 18 months. The cheapest 30 day contract with data seems to be around £10, this equates to a £109 saving over 18 months. I'm more than happy to pay that (£6/month) to stay with a more reliable carrier (by that I mean one that is less likely to steal from you), spread the cost of the hardware and get visual voice mail. The only significant restriction is that I can't sell the hardware, which considering I'm still on a 3G is unlikely to be a problem.