The 12 month contract that I took out when purchasing my iPhone is just about to end, so I am looking at switching to a new contract (most likely a SIM only contract).
I currently use Tesco Mobile (which uses the O2 network). 3G coverage is no more than okay at best. Having said that, there's been a few times when I have struggled to get even a cellular connection (most notably in parts of Wales).
So, is anybody able to recommend a network that has good coverage and speeds? Vodafone have some good deals on SIM only contracts (particularly if you use Quidco to get cashback), but I've read a number of bad things about their customer service.