I personally hate the fact that the networks have changed standard contracts from 12mths to 18/24mths with very little or no cost benefits to the consumer. I've had a mobile on contract for years and was always getting great deals on 12mth extentions.
Last phone upgrade was a Blackberry on 18mth deal, and now moved to HTC Desire in July to a 18mth, 600mins, 3,000 txts (sold as unlimited) and 1GB Internet for £30 per month with the phone for free. Also managed to get £30 credit for the first month, becuase the phone was delayed in getting to me. So in total £510 on this contract, which seems a pretty fair deal.
Next time though I will possibly buy the phone outright and move to a rolling or 12mth sim only contract, but the truth is it will probably cost me more (unless buying an iPhone), but I'll have more freedom, no firmware hassle and reduction in monthly spend.