I was with three for 5 years. The coverage was excellent for me, the 3G signal being robust and HSDPA lightning fast. For me their only downside was a lack of decent handsets which made me switch to Vodafone with an n97 (total waste of time, both handset and network 3G wise) so I switched to O2 for the iphone 3gs. o2's 3G is better than Voda for me here in Birmingham but I must admit it's not a patch on three's. If I wasn't mid contract now, I would happily take the iphone on three.